Roll-up tarp apparatus

ABSTRACT

A roll-up tarp apparatus for a truck box having first and second ends, first and second longitudinal sides and an open top. The apparatus includes a tarp, a roll bar, an arm and a biasing member. The first longitudinal edge of the tarp is interconnected to the first longitudinal side of the truck box and the second longitudinal edge of the tarp is attached to the roll bar member. The roll bar is operatively connected to the truck box and is rotatably movable between the first and second longitudinal sides of the truck box, which enables the tarp to close or open the truck box. At least one biasing member is operatively connected to the roll bar or the arm, with the biasing member able to exert a tensioning force in the direction of the second longitudinal side of the truck box so that the tarp is under tension.

This application claims priority to U.S. Provisional Application Ser. No. 61/051,999 entitled “Roll-Up Tarp Apparatus,” filed on May 9, 2008 and U.S. Provisional application Ser. No. 61/169,185 entitled “Roll-up Tarp Apparatus,” filed on Apr. 14, 2009, the disclosures of which are herein incorporated by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Invention

The present invention relates to roll-up tarp apparatuses for an open top truck cargo box or the like. More particularly, the present invention relates to roll-up tarp apparatuses including an elongated roll bar member that is biased with at least one biasing member.

2. Description of the Related Art

Roll-up tarp apparatuses for truck cargo boxes having an open top are widely utilized in the trucking industry. For example, U.S. Pat. No. 4,505,512 (Schmeichel et al.) discloses a roll-up tarp apparatus for an open truck box or trailer. The roll-up tarp apparatus includes a tarp made from a flexible material. The tarp is secured along one side to the top of the truck box. The other side of the tarp is attached to a roll bar with a plurality of flexible straps. A crank apparatus connected to the roll bar by a U-joint and collar assembly is utilized to roll the tubular member transversely of the truck box opening so as to selectively enclose the truck box with the tarp or uncover the truck box. A plurality of hooks is attached to the side of the truck box opposite of the side to which the tarp is fixedly secured. The hooks retain the roll bar when the tarp is covering the truck box. Other known roll-up tarp assemblies utilize a crank to control the movement of the roll bar and others, such as that of U.S. Pat. No. 4,673,208 (Tsukamoto) utilize a motorized arm that is interconnected to the roll bar.

In motorized roll-up tarp apparatuses, a biasing member can be used to assist the motor in moving the roll bar in an unroll direction. Typically, a bungee cord is interconnected to a collar located on the roll bar extends from the collar, around a corner of the truck box and along at least part of the length of the truck box where the second end of the bungee cord is attached. As the tarp is rolled-up across the top opening of the truck box, the bungee cord typically stretches and rubs against the corner of the truck box. The constant stretching of the bungee cord along the corner of the truck box is a constant source of abrasion on the cord, thus reducing the life of the bungee cord and increasing the strain on the motor when the cord is at a reduced biasing capacity. As the roll bar rolls up or unrolls the tarp, the arms move the roll bar across a frame that supports the tarp over top opening of the truck box.

Other known roll-up tarp assemblies include springs to bias the arms in the unroll direction. Spring assists are typically used when the tarp is un-rolled from the front to the back, rather than side to side. See, for example, U.S. Pat. Nos. 7,188,887 (Schmeichel) and 7,195,304 (Schmeichel).

The present invention addresses limitations and problems associated with the related art.

SUMMARY OF THE INVENTION

The present invention provides roll-up tarp apparatuses for an open truck box or the like. The preferred roll-up tarp apparatus includes a tarp made of a flexible material having first and second longitudinal sides. One longitudinal side can be attached to a longitudinal side of the truck box and the second longitudinal side is connected to an elongated roll bar member of the roll-up tarp apparatus such that when the elongated roll bar member moves across the truck box in one direction, the tarp is un-rolled from the roll bar to cover the opening of the truck box and when the roll bar moves in a second direction, across a middle of the truck box, the tarp is rolled-up and gathered on the elongated roll bar member. In order to facilitate movement of the elongated roll bar member, one preferred roll-up tarp apparatus includes at least one arm having a top end and a bottom end. Optionally, the top end of the arm is connected to a motive source with a motor, which is interconnected to the elongated roll bar member to selectively move the roll bar in unroll and roll-up directions to respectively cover and uncover the opening of the truck box. Alternatively, a crank arm assembly can be used to move the elongated roll bar member. The bottom end of the arm can be pivotally interconnected to one opposing end of the truck box.

The preferred arm includes a shaft and a sleeve that is moveable along the shaft. The preferred shaft has a restricting member such that as the arm moves, the sleeve slides upwardly and downwardly along the shaft until the sleeve contacts the restricting member, which prevents the sleeve from moving downward past that point. The restricting member is preferably positioned on the arm such that the elongated roll bar member will be supported substantially over an apex of the truck box when the arm is at an angle of about 90 degrees with respect to a lateral ends of the truck box such that any cargo defining a crowned top surface (e.g. grain when initially loaded into the truck box) can be cleared by the elongated roll bar member. In the most preferred embodiments, the position of the restricting member is adjustable. The higher the elongated roll bar member is supported above the truck box, the more wind can make operation of the roll-up tarp assembly difficult. Therefore, it is preferred that a user can adjust the height the restricting member will support the elongated roll bar member for the particular conditions present. Alternate embodiments can include a resilient restricting member, such as a spring.

Further, in preferred embodiments, the roll-up tarp assembly includes at least one roll bar biasing member connected to one of the ends of the elongated roll bar member and, in preferred embodiments, two roll bar biasing members, one connected to each of the respective ends. The roll bar biasing member(s) exerts a force on the roll bar member that places a tension on the roll bar member and can urge the movement of elongated roll bar member in the unroll direction when motive force is provided to rotate the roll bar. In preferred embodiments, one biasing member is connected to each end of the elongated roll bar member such that the forces exerted on each end of the roll bar member are generally equal or, alternatively, not equal but the greatest at those positions. Preferably, the roll bar biasing members each include a cord interconnected to one end of the elongated roll bar member; wherein the cord winds around the elongated roll bar member as the arm directs the elongated roll bar member in the unroll direction. Preferably, each biasing member includes a tensioning element having first and second ends, the first end of the tensioning element is interconnected to the cord and the second end of the tensioning element is interconnected to the second longitudinal side of the truck box. In preferred embodiments, an unwound portion of the cord and the biasing member are arranged and configured such that they are generally perpendicular to the elongated roll bar member and continually tension the elongated roll bar member not only in the unroll direction but also when the elongated roll bar member is in the latched or secured position. Because the roll bar biasing member is generally perpendicular to the elongated roll bar member, the cord will have a self-aligning tendency, which will provide for generally equal movement of both ends of the elongated roll bar member.

Various preferred roll-up tarp apparatuses include upper and/or lower arm biasing members interconnected to the top end (or a slidable upper sleeve, as the case may be) and the bottom end, respectively, of at least one arm. The preferred upper arm biasing member includes an elastic cord interconnected to a generally non-elastic cord and is configured such that the generally non-elastic cord will be drawn around the corner of the truck box whereas the elastic cord will extend only along the longitudinal side of the truck box and tarp. The preferred lower arm biasing member includes a torsion spring that urges movement of the respective arm, and thus also the elongated roll bar member, in the unroll direction. The arm biasing members urge the respective arm in the unroll direction, thus indirectly biasing the elongated roll bar member in the unroll direction.

In another preferred embodiment, at least one arm with a motive source is provided with a converter unit or unit having an input section that is connected to the motive source and an output section that is connected to the elongated roll bar member. The converter unit includes a plurality of interconnecting elements or components that are arranged so that they are able to change the characteristics of the motive source so that they are different at the output section of the unit. The interconnecting elements include rotatably mounted wheels and an endless belt, although sprockets and a chain are preferred. The sprockets can have different sizes that can effectively change the torque and speed of rotation of the motor produced at the output section of the unit. Preferably, the sprockets of the unit are selected so as to be able to effectively increase the torque of the motor at the output section of the unit.

Various preferred roll-up tarp apparatuses are arranged and configured such that the cord of the biasing member winds around the elongated roll bar member such that a substantial portion of the wound-up cord is protected and stowed underneath the latch plate when the elongated roll bar member is in the latched position or, alternatively, the secured position. Further various preferred biasing members can be arranged and configured to exert continual tension on the elongated roll bar member. Continual tension exerted on the elongated roll bar member, particularly when the roll bar member is in the secured position, is advantageous because, among other reasons, the tension can substantially eliminate lateral swinging of the elongated roll bar member during transit, which could damage the truck box and pose other safety concerns, especially if the elongated roll bar member were to become disengaged from the latch plated.

These and various other advantages and features of novelty which characterize the present invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, in which corresponding reference numerals and letters indicate corresponding parts of the various embodiments throughout the several views, and in which the various embodiments generally differ only in the manner described and/or shown, but otherwise include corresponding parts;

FIG. 1 is a perspective view of a roll-up tarp apparatus 10 operatively secured over a trailer or a truck box 6 of a truck 5 and showing the elongated roll bar member 18 in a partially open position;

FIG. 2A is an enlarged end view of the front, right corner of the truck box 6 shown in FIG. 1;

FIG. 2B is a view similar to that of FIG. 2A, but illustrating an alternate method of securing the upper biasing member 50 a to the elongated roll bar member 18 with a rotatable collar 80;

FIG. 3 is a partial, perspective view of a rear arm 22 b of the roll-up tarp apparatus 10 shown in FIG. 1;

FIG. 4 is an abbreviated perspective view of attachment portions of the initial preferred upper biasing member 50 a of the roll-up tarp apparatus 10 of FIGS. 1-2;

FIG. 5 is a partial, schematic, end view of the truck box 6 illustrating a front arm 22 a of FIG. 2A further including a restricting member 38 a that can support a tarp 12 above the end cap 8 e of the truck box 6;

FIG. 6A is a partial, schematic, end view of the truck box 6, similar to that shown in FIG. 5, wherein there is cargo C is particulate material such as grain, delivered into the truck box 6 and the restricting member 38 a is supporting the elongated roll bar member 18, and thus, the tarp 12 above a mound of the newly delivered cargo C;

FIG. 6B is a partial, schematic view of the arm 22 a as shown in FIG. 6A, but showing an alternate restricting member 38 b and including a resilient compression spring 42;

FIG. 6C is a partial, schematic view of the arm 22 a as shown in FIG. 6A, but showing an alternate restricting member 38 c;

FIG. 6D is a partial, schematic view of the arm 22 a as shown in FIG. 6A, but showing yet another alternate restricting member 38 d;

FIG. 6E is a partial, schematic view of the arm 22 a as shown in FIG. 6A, but showing yet another alternate restricting member 38 e;

FIG. 7A is a schematic, end view of the elongated roll bar member 18 as it is in the process of being secured over the trailer or cargo box 6, prior to being in a closed, stored or secured position; the cargo box 6 contains a new load of cargo C such as grain or the like, which is shown in a mound in the center prior to the usual shifting of the load that occurs over time after the load is delivered, similar to that shown in FIG. 6A;

FIG. 7B is a schematic, end view of the elongated roll bar member 18 similar to that shown in FIG. 7A, but as the elongated roll bar member 18 is stored in the secured position and illustrating how the flexible cover 12 is tensioned downwardly to compress the cargo C down into the truck box 6 as the tarp 12 is tightened on the elongated roll bar member 18 against the latch plate 64 a;

FIG. 8 is an enlarged view of a lower arm biasing mechanism 100 of FIG. 1;

FIG. 9 is an alternate embodiment of an arm 22 a′, the alternate arm 22 a′ interconnected to the side 8 a of the truck box 6 with a ball joint 95 and showing the ball 93 in phantom;

FIG. 10 is a side, schematic view of the arm 22 a′ of FIG. 9, illustrating the preferred adjustable range of the arm 22 a′ allowed by the ball joint 95;

FIG. 11 is a partial perspective view of an alternate biasing member 150 connected to one end of the elongated roll bar member 18 of an alternate roll-up tarp apparatus similar to that shown in FIG. 1; but portions of which are shown in phantom;

FIG. 12A is a partial perspective view of the end of the elongated roll bar member 18 of FIG. 11 (certain elements have been omitted for clarity);

FIG. 12B is a partial perspective view of the end of an alternate flexible tarp 12′ connected to the elongated roll bar member 18 of FIG. 11;

FIG. 13A is a partial cross-sectional view of the end of the elongated roll bar member 18 of FIG. 12A;

FIG. 13B is a partial, end view of the elongated roll bar member 18 and tarp 12′ of FIG. 12B when the elongated roll bar member is in an unrolled position;

FIG. 14 is a partial side view of an attachment plate 270 for securing a spring 156, which is a portion of the alternate biasing member 150 of FIG. 11 to the first side 8 b of the truck box;

FIG. 15 is a front view of the attachment plate 270 of FIG. 14;

FIG. 16A is a partial, schematic end view of the biasing member 150 of FIG. 11, biasing the elongated roll bar member 18 toward the closed position when the elongated roll bar member 18 is secured in an open position and the cover 12 is rolled up on the elongated roll bar member 18;

FIG. 16B is a partial, schematic end view of the elongated roll bar member 18 as the elongated roll bar member 18 moves toward the secured position of FIG. 16C;

FIG. 16C is a partial, schematic end view of the elongated roll bar member 18 in the secured position, wherein the flexible cover 12 is over the truck box 6 so that the truck box opening (7 a, not shown) is closed;

FIG. 17A is partial, schematic end view of a second alternate biasing member 250, similar to that shown in FIG. 11, but including a pulley 266;

FIG. 17B is partial, schematic end view of the second alternate biasing member 250 of FIG. 17A as the elongated roll bar member 18 is moving toward the secured position;

FIG. 17C is partial, schematic end view of the second alternate biasing member 250 of FIG. 17A when the elongated roll bar member 18 is in the secured position;

FIG. 18A is a schematic illustration of the elongated roll bar member 18 as it moves from the secured position P1 to the open position P6;

FIG. 18B is a partial, schematic illustration of alternate configurations of the roll-up tarp assembly of FIG. 11 in which the biasing member 150′, 150″, 150″′ can at least partially be secured at numerous positions within the truck box 6 (as also shown in phantom);

FIG. 18C is an enlarged schematic illustration of cord 158′ of FIG. 18B exiting the truck box 6 through grommet 170;

FIG. 19 is a partial, perspective, schematic view of arm 22 a including a motive source 30 and a converter unit 300 to multiply to force of the motive source;

FIG. 20 is a top plan, schematic view of the converter unit 300 of FIG. 19;

FIG. 21 is a schematic illustration of the internal arrangement of the components or elements of the converter unit 300 of FIG. 19;

FIG. 22 a is a first graphical representation of the tension (lbs. of tensioning force) on the cord 158 of one preferred embodiment of the biasing member 150 when the elongated roll bar member 18 is in positions P1 through P6 as illustrated in FIG. 18A;

FIG. 22 b is a second graphical representation of the tension (lbs. of tensioning force) on the cord 158 of a second preferred embodiment when the elongated roll bar member 18 is in positions P1 through P6 as illustrated in FIG. 18A;

FIG. 23 is a partial, perspective view of a crank arm assembly 400 connected to the elongated roll bar member 18, which can be substituted for the motive force 30 of the roll-up tarp apparatus 10 of FIG. 1;

FIG. 24 is an exploded, perspective view of the elongated roll bar member 18 of FIGS. 1 and 11-13; and

FIG. 25 is an end view of the elongated roll bar member 18 of FIGS. 1, 11-13 and 24.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-3 illustrate a truck 5 including a truck cargo box or truck box 6 having a bed and four sides 8 a-d. In preferred embodiments, the truck box 6 can include one or two end caps 8 e and 8 f secured over a top 7 of the respective ends 8 a, 8 c of the truck box 6. Each end cap 8 e, 8 f includes an end edge, opposing side edges, and a curved outer surface. Note that the top 7 of the truck box 6, which defines a top opening 7 a, will be somewhat foreshortened by the use of one or more end caps 8 e, 8 f. Although in some cases, the roll tarp assemblies of the present invention will not include end caps, because they are sometimes provided by the truck manufacture or have been provided with a previously used roll tarp apparatus, the present invention can include end caps provide for each end of the truck box 6. Similarly, support bows 9, if required and provided, can be provided by the manufacturer of the truck box 6 or alternately provided as a part of an alternate roll-up tarp apparatus. A preferred roll-up tarp apparatus 10, operatively secured to a truck box 6, is shown in these figures. The roll-up tarp apparatus 10 includes a flexible tarp 12 that can be drawn over the top opening 7 a to cover cargo C (see FIGS. 6A, 6B) within the truck box 6, an elongated roll bar member 18, two arms 22 a, 22 b positioned at each of the respective ends 8 a, 8 c of the truck box 6 and connecting members 44 a, 44 b that connects the roll bar member 18 to the respective arms 22 a, 22 b. The arms 22 a, 22 b selectively control the position of the elongated roll bar member 18, as it is rolling-up (furling) or unrolling (unfurling) the tarp 12. In alternate embodiments of the present roll-up tarp apparatus, discussed herein, there may be only one arm provided.

The preferred flexible tarp 12 is made of vinyl coated polyester preferably having a weight of from about 10-22 oz/yd², preferably about 18 oz/yd², although lighter or heavier material could be used. The flexible tarp 12 includes two longitudinal edges 14 a, 14 b and to lateral edges 16 a, 16 b. One longitudinal edge 14 a of the flexible tarp 12 is attached to one respective side 8 d of the truck box 6. The other longitudinal edge 14 b of the flexible tarp 12 is secured to the elongated roll bar member 18, which is interconnected to two arms 22 a, 22 b that are pivotally attached to the respective ends or lateral ends 8 a and 8 c of the truck box 6.

The roll-up tarp apparatus 10 preferably further includes a latch plate or rail 64 a, 64 a′ and a plurality of posts or stops 65. The latch plate 64 a, 64 a′ is preferably removably positioned along one side 8 b of the truck box 6, while the support posts 65 are positioned in a spaced apart relation along the opposite side 8 d. The latch plate 64 a, 64 a′ includes an innermost edge with a vertically oriented attachment flange 64 h, 64 h′ and a downwardly facing curved or arcuate surface 64 d, 64 d′ that is configured and arranged to receive the elongated roll bar member 18 when the roll bar member is in the latched and secured position. The downwardly facing curved or arcuate surface 64 d, 64 d′ includes an inner longitudinal edge 64 b, 64 b′ and an outer longitudinal edge 64 c, 64 c′. The vertical flange 64 h, 64 h′ can further be attached to a spacer 64 i, 64 i′ serves to space the inner longitudinal edge 64 b, 64 b′ of the downwardly facing curved surface 64 d, 64 d′ away from the side 8 b of the truck box 6, preferably by about ¼ inch to about 1¼ inch. As best illustrated in FIGS. 2A and 11, the preferred latch plate 64 a, 64 a′ is arranged and configured such that the elongated roll bar member 18 including the wound up tarp 12 is spaced away from and out of contact the side of the truck box 8 b by spacer 64 i, 64 i′ when the elongated roll bar member is underneath the latch plate 64 a, 64 a′ either in a stored position or otherwise.

As generally illustrated in FIG. 11 and further discussed below, the latch plate 64 a′ need not be a unitary structure. The latch plate 64 a′ can be segmented and include a plurality of spaced apart sections of any effective length spanning the length of the truck box 6. For example, the latch plate 64 a′ can include three sections, one at each end of the truck box 6 and one in the middle. This generally prevents unnecessary wear damage to the side of the truck box. Preferably, the latch plate 64 a′ is provided with spacer 64 i′ that positions the inner longitudinal edge 64 b′ of the downwardly facing receiving surface 64 d′ of the latch plate away from the side of the truck box 8 b; preferably by about 0.25 inch.

Further preferred latch plates 64 a, 64 a′ include an outer longitudinal edge 64 c, 64 c′ with a rounded surface 64 f, 64 f′ over which both the flexible tarp 12 and the non-elastic cord 58 can be drawn. Such a rounded surface provides a controlled surface with a smooth transition that can reduce wear as compared to when the flexible cover 12 and cord 58 are drawn over the comparatively sharp, angled edge of the truck box 6, which can be rough and abrasive. Optionally, the rounded surface 64 f, 64 f′ may include an upwardly facing longitudinal channel 64 g, 64 g′ that is configured and arranged to receive moisture and direct it towards the ends of the latch plate 64 a, 64 a′.

The truck box 6 will preferably include support bars or ribs 9 that span the respective longitudinal sides 8 b, 8 d of the truck box 6 and which provide support for the tarp 12 above the top opening 7 a of truck box 6. Moreover, each end cap 8 e, 8 f is attachable to one end 8 a, 8 c of a truck cargo box 6 such that their respective edges meet, and their respective curved upper surfaces 25 are able to support a portion of a flexible tarp 12 of a roll-up tarp assembly 10 when the tarp assembly 10 is in a secured position or when the tarp assembly is moving between secured and open positions.

Referring now also to FIGS. 5 and 6A, it is noted that preferred roll-up tarp apparatus embodiments will include two arms 22 a, 22 b, one at each end of the truck box 6. Each of the arms 22 a, 22 b will preferably include a shaft 36 a, 36 b and a sleeve 32 a, 32 b. The shafts 36 a, 36 b are pivotally connected to respective ends 8 a, 8 c of the truck box 6 at a point of attachment 23 (see, FIG. 5, only one point of attachment 23 for arm 22 a is illustrated, however, it will be understood that the second arm 22 b will be attached to the truck box 6 in a similar manner). Generally, each sleeve 32 a, 32 b is able to freely slide upwardly and downwardly on top ends 24 a, 24 b of respective arm shafts 36 a, 36 b so that the roll bar 18, which is connected to the sleeve, is able to follow the general contour of the end plate 8 e as opposed to following an arc described the top end 24 a of the arm 22 a, 22 b. In other words, the interaction of the shaft 36 a, 36 b and sleeve arm 22 a, 22 b are able to accommodate a varying or variable distance D, wherein the distance can be measured from the center of the pivotal point of attachment 23 and a variable point of contact. The point of contact can be, for example, established by the elongated roll bar member 18 as it traverses over the end cap 8 e (in general terms, over the top 7 of the truck box 6, which is generally the resting place for the roll bar 18 when the tarp 12 is mostly unrolled as shown in FIGS. 2A, 2B and 3). The point of contact can also be established by the bottom most portion of the flexible tarp 12 as the tarp is rolled-up (or furled) on the elongated roll bar member 18 and contacts the upper surface 25 of the respective end cap 8 e, 8 f, which is interposed between the top 7 of the truck box 6. It will be appreciated that this variable distance D changes both: 1) as a distance between a variable location on the top 7 of the truck box 6 or the upper surface 25 of the respective end cap 8 e, 8 f and the respective center point of pivotal attachment 23 varies through a turn radius of the respective arms 22 a, 22 b; and 2) as the tarp 12 is rolled-up on the elongated roll bar member 18 creating varying thickness of gathered tarp 12 on the elongated roll bar member 18. For instance, in the embodiment shown in FIGS. 1-3 and schematically in FIGS. 5 and 6A, the top opening 7 a is almost completely uncovered when the arms 22 a, 22 b are over as far as they can go to the left (as shown schematically in phantom in FIG. 5). In this situation, the tarp 12 (not shown for clarity in this Figure) will be almost completely rolled-up on the elongated roll bar member 18 and the gathered tarp 12 (see also, FIGS. 2A and 3), which is rolled up on the elongated roll bar member 18 will rest against the respective support posts 65 and on the upper surface 25 of the respective end caps 8 e, 8 f.

It will be further appreciated, that the thickness of the gathered tarp 12 (see also, FIGS. 2A and 3) on the roll bar member 18 will not lift the roll bar 18 from the upper surface 25 of the respective end caps 8 e, 8 f on each end of the truck box 6, when the roll bar member 18 is close to the edge of the truck box when the tarp is nearly covering the entire top opening 7 a. In alternate embodiments, where the end caps 8 e, 8 f are lower than the bows, support bars or ribs 9 that are provided with the various truck box 6 manufactured in North America, the bottom portion of the rolled-up tarp 12 (see also, FIG. 2A) may rest on the bows 9, raising the roll bar member 18 the distance of the thickness of the tarp gathered on the roll bar as it rests on the bows 9 proximate the respective ends 8 a, 8 c of the truck box 6 and thereby separating the roll bar member that further distance from the respective points of attachment 23 and raising the rolled-up tarp above the upper surface 25 of the respective end caps 8 e, 8 f for a short interval during the respective roll-up and unroll processes. Preferably, the bows 9 are positioned slightly higher than the end caps 25 to further tension and spread the tarp 12 across the truck box opening 7 a. It will also be appreciated that as the roll bar member 18 moves over the top opening 7 a in the direction of the other longitudinal side 8 b of the truck box 6, and the tarp 12 is being unrolled in order to cover the top opening 7 a, the space between the roll bar member 18 and upper surface 25 of the respective end caps 8 e, 8 f will gradually diminish. Because the arms 22 a, 22 b are also turning through a path (not designated) that may differ from a contour or radius R of the end caps 8 e, 8 f of the truck box 6 or the upper surface 25 of the end caps 8 e, 8 f interposed between the top opening 7 a and the roll bar member 18, the variable distance D is also subject to change.

In any case, it will be appreciated that the respective sleeves 32 a, 32 b make upward or downward adjustments with respect to the respective shafts 36 a, 36 b to accommodate these variations in space and distance, so that the roll bar member 18 can rotate from left to right away from the support posts 65, toward the latch plate 64 a, 64 a′, in an unroll direction, shown in phantom in FIG. 5 or rotate from right to left away from the latch plate 64 a, 64 a′ and toward the support posts 65 as the tarp 12 is rolled-up or furled on the roll bar member 18 and the top opening 7 a is uncovered and open (see also, FIG. 5).

In the most preferred embodiments of the present invention, selective movement of one arm 22 a is actuated by a motive source 30 having a motor 31. In preferred embodiments, the motor 31 will be either an electric motor or a hydraulic motor, although other suitable motors may also be used. In the most preferred embodiments, the motor 31 will be a Super Winch Power Drive (Model No. 719627 from Super Winch, Inc. of Putnam, Conn.), which includes a worm gear (not shown) that drives the turning of the elongated roll bar member 18. As shown in FIG. 2A, the motor 31 can be attached to the sleeve 32 a and connected to an electrical power source 33, as shown in FIG. 1, by electrical conduit 34. It will be appreciated that other power sources may also be used including, without limit, a truck battery (not shown) or a power take off (PTO) (not shown). Although it is within the scope of the present invention to provide a second motive source (not shown) to actuate selective movement of the roll bar member 18 from the back end 8 c of the truck box 6, in coordination with the selective movement of the roll bar member 18 actuated by the motor 31 associated with the arm 22 a on the front end of the truck box 6, it is believed that a second motive source is unnecessary to provide the necessary actuating assistance needed to either: 1) roll-up the tarp 12 as the roll bar member 18 moves in the roll-up direction; or 2) unroll the tarp 12 as the roll bar member 18 moves in the unroll direction and the tarp 12 is unrolled to cover the top opening 7 a. It will be appreciated that the selective movement of the roll bar member 18, in either the unroll or the roll-up direction, may be actuated by a hand crank of a type that is well known in the art, including that disclosed in U.S. Pat. Nos. 4,505,512; 5,823,067 and 6,135,534, the disclosures of which are hereby incorporated herein by reference (see also, FIG. 23). One of the great advantages of using a worm gear type motor, is the screw portion of the worm gear acts as a stop or lock against any un-rolling of the roll bar member when the roll bar member is motionless in any position, especially in the fully closed position, when the roll bar member is secured up against the latch plate 64 a. In that position, it is especially important to maintain tension on the roll bar member 18 so that it does not loosen up during transit and begin to flop around and bang against either the latch plate or the side of the truck box 6. The worm gear type motor, which is preferred, significantly reduces the likelihood that the roll bar member 18 will unroll and loosen with respect to its engagement with the latch plate 64 a.

FIG. 2A also illustrates an upper or roll bar biasing member 50 a interconnected to the arm 22 a. A second upper or roll bar biasing member 50 b can be provided at the back end 8 c of truck box 6 and secured to the second arm 22 b, for example, as shown in FIG. 3. The upper biasing members 50 a, 50 b are provided in preferred embodiments to assist the motive source 30 in moving the arms 22 a, 22 b, and indirectly the roll bar member 18, in the unroll direction or in other words, in a direction towards the second longitudinal side 8 b of the truck box 6. The preferred upper biasing members 50 a, 50 b that are interconnected to the arms 22 a, 22 b are preferably connected to the truck box 6 with a retaining strap 70 on the longitudinal side 8 b of truck box 6 as illustrated in FIG. 4 and extend along at least part of a longitudinal side 8 b of the truck box 6 and preferably to the respective arm 22 a, 22 b, where it is attached to the respective sleeve 32 a, 32 b; or alternatively, the elongated roll bar member 18 as shown in FIG. 2B.

In order to prevent wear damage of the biasing members 50 a, 50 b, a corner guide 66 a, 66 b, 66 c is preferably provided. Each corner guide 66 a, 66 b, 66 c includes a base 67 a and an orthogonally oriented flange 67 b. The base 67 a is provided with an aperture 67 c that receives a fastening element, and the flange, which extends outwardly from the base, is provided with transverse slot 67 d that is in communication with the aperture 67 c. A cord 58 may be connected to by corner guide 66 a, 66 b, 66 c by passing it between arms formed by the slot 67 d and into the aperture 67 c. Preferably, the edges of the aperture 67 c are rounded and the surface of the aperture is provided with a low-friction material. More preferably, corner guide 66 a, 66 b, 66 c is plastic. The guide 66 a, 66 b, 66 c can be aligned either horizontally (see FIG. 2A) or vertically aligned (see FIG. 2B).

FIG. 2B illustrates the upper biasing member 50 a somewhat differently configured as compared to FIGS. 1-2A. The upper biasing member 50 a extending through corner guide 66 c that is arranged such that the generally non-elastic or generally non-extendable cord 58 of the upper biasing member 50 a passes through the corner guide 66 c and is directed generally perpendicular to the latch plate 64 a to where the upper biasing member 50 a can be interconnected to the elongated roll bar member 18 with a rotatable collar 80 by way of a D-shaped ring 82, that is attached to the collar and which extends radially therefrom. Alternate embodiments of the roll tarp assembly of the present invention can have one collar 80 at each end of the roll bar member 18 so that the roll bar member is tensioned at each of its respective ends. The collar 80 is can be arranged and configured such that it is easily and freely rotatable about the elongated roll bar member 18 such that as the elongated roll bar member 18 rotates and moves over the upper surfaces 25 of the respective end caps 8 e, 8 f at each end of the truck box 6, neither of the two respective generally non-elastic cords 58 will wind around the elongated roll bar member 18.

It will be appreciated that alternate embodiments of the roll-up tarp apparatus 10 may be configured to have one arm at each end of the truck box 6, with each arm provided with a connecting member 44 a, 44 b that is connected to opposite ends of the elongated roll bar member 18. Upper biasing members 50 a, 50 b can be interconnected between the latch plate 64 a or truck box 6 and one of the respective arms 22 a, 22 b, or alternatively, one of the respective ends of the elongated roll bar member 18. It will be appreciated that the respective upper biasing members 50 a, 50 b can also be attached to the respective arm 22 a, 22 b at one end and to the roll bar member 18 at the other end. Furthermore, in certain truck cargo box configurations, where the rear end of the truck box opens, an arm at the rear end would likely interfere with the opening and closing operations. For that reason, and also because the cost of the addition arm may be a factor, arms at both ends are unnecessary and a single simple arm, preferably located at the front, may be provided and the rear end of the elongated roll bar member will be connected to the latch plate or truck box with an upper biasing member of the present invention or by other biasing members of the type that have been disclosed in the prior art, e.g. the bungee cord engaged with the roll bar member as disclosed in U.S. Pat. No. 4,505,512 (Schmeichel), the disclosure of which is hereby incorporated herein by reference. Furthermore, it will be appreciated that the roll-up tarp assembly may be either motorized or manually driven. In the manually driven embodiment, power to the arm will be provided by a hand crank, similar to those now in use and publicly disclosed in the patent literature and elsewhere (see, FIG. 23). It will be appreciated that a crank arm assembly or handle is relatively dissimilar to the arms of the present invention, insofar as it is not pivotally connected to the truck box. In this regard, it will be further appreciated that the upper biasing member of the present invention may be provided in yet another alternate embodiment in which the motive source is a hand crank and each end of the elongated roll bar member is interconnected to the truck box by a biasing member, either or both of which may be an upper biasing member attached to a collar (see, for example, FIG. 2B) secured to the elongated roll bar member. In alternate embodiments, the cord can be securely attached to the roll bar member such that the cord winds around the elongated roll bar member as the tarp is opened and unwinds as the tarp is unwound (see, for example, FIG. 12A, 12B). In such embodiments, the arm can be a crank handle and it will not be pivotally connected to the end of the truck box or trailer, but a biasing member of one type or another will be provided. The biasing member may be an upper or roll bar biasing member of the present invention, preferably one interconnected to the latch plate at each end of the roll bar member, but other biasing members and mechanisms that are well known in the art may also be used.

It will be further appreciated that various types of arms can be used. For example, hinged or biased arms can be utilized. Examples of such arms are disclosed in U.S. Pat. No. 7,188,887 (Schmeichel), the disclosure of which is herein incorporated by reference.

The upper biasing member 50 a, 50 b is preferably interconnected directly to the respective arm 22 a, 22 b even more preferably, to the sleeve 32 a, 32 b of the respective arm 22 a, 22 b. In the preferred embodiment shown in FIG. 4, the upper biasing member 50 a includes an elastic member or cord 56. The elastic member or cord 56 is preferably a stretch cord, bungee cord, shock cord, elastic rope or the like having an extensibility of at least about 60% greater than its relaxed, unstressed state, more preferably at least about 80%, even more preferably about 100%, and even more preferably at least about 130%. When the upper biasing member 50 a, 50 b is interconnected directly to the respective arm 22 a, 22 b, the upper biasing member 50 a, 50 b will not wrap around the elongated roll bar member 18. The sleeve 32 a, 32 b can include a connecting ring 40 a, such that the upper biasing member 50 a, 50 b can simply be clipped on to a sleeve 32 a, 32 b of the respective arm 22 a, 22 b with a clip 62, such as a carabineer or the like. It will be appreciated that any other known connecting device may be used as an alternative to the clip.

The rear arm 22 b is similar to the front arm 22 a as discussed herein, but is preferably interconnected to the elongated roll bar member 18 with a connecting member 44 b. The connecting member 44 b is similar to sleeve 32 a of the first arm 22 a in that the connecting member 44 b is adjoined to the sleeve 32 b, which can slide along the shaft 36 b of the arm 22 b as the elongated roll bar member 18 is moved in the roll-up and unroll directions. FIG. 2A also illustrates an upper biasing member 50 a interconnected to the arm 22 a. Preferably, a second upper biasing member 50 b is additionally provided to assist the motive source 30 in moving the rear arm 22 b in the unroll direction. The second upper biasing member 50 b also is largely similar to the first upper biasing member 50 a as previously discussed and is preferably connected to a second retaining strap 70, just as illustrated in FIG. 4, which extends along at least part of a longitudinal side 8 b of the truck box 6 and to the respective arm 22 b, or alternatively, the elongated roll bar member 18. The second upper biasing member 50 b of FIG. 3 is preferably interconnected directly to the respective arm 22 b, even more preferably to the sleeve 32 b of the respective arm 22 b. The sleeve 32 b can include a connecting ring 40 b, such that the upper biasing member 50 b can simply be clipped on to the sleeve 32 b of the respective arm 22 b with clip 62, such as a carabineer or the like.

In some preferred embodiments, the roll-up tarp assembly 10 will include only one arm 22 a located at the front end 8 a of the truck box 6 to accommodate truck boxes 6 having a rear end 8 c that opens (not specifically illustrated). In these embodiments, the rear upper biasing member 50 b can be interconnected to the elongated roll bar member 18 with the rotatable collar 80 similar to the arrangement and configuration illustrated in FIG. 2B.

Referring now also to FIG. 4, in preferred embodiments, the upper biasing members 50 a, 50 b on each end of the truck box 6 will be two different interconnected cords, one of which is an elastic cord 56 such as a stretch cord, bungee cord, shock cord, elastic rope or the like and the other of which is a generally non-elastic cord 58, which is joined to the elastic cord 56 to form the two-piece biasing member 50 a, 50 b. In providing the two-piece biasing member 50 a, 50 b, the inventors have constructed and arranged the elastic cord 56 in such a way that the elastic portion 56 of the biasing member 50 a, 50 b is not required to stretch through the respective corner guide 66 a, 66 b, 66 c, which would be abrasive for the elastic cord 56, were it required to turn and stretch out toward the respective sleeve 32 a, 32 b, when the respective arm 22 a, 22 b is moving in the roll-up direction and the roll bar member 18 is moving toward the support posts 65. In other words, the generally non-elastic portion 58 of the respective upper biasing member 50 a, 50 b is preferably long enough and the elastic portion is short enough such that the elastic portion 56 will not extend around respective corner guide 66 a, 66 b, 66 c of the truck box 6 when the elongated roll bar member 18 is in the fully open position proximate the support posts 65. It will be appreciated that as either cord 56, 58 passes through such a corner guide 66 a, 66 b, 66 c, in many circumstances the cord will be required to pass over an edge, which will likely abrade the cord, especially if it is an elastic cord such as a bungee cord. Elastic cords are generally especially subject to wear as they pass over hard edges, because they have an outer woven “skin” or “jacket.” The design of the jacket allows the elastic inner cord to stretch as the woven material of the jacket is draw straight to allow the inner elastic cord material to stretch. The jacket is highly subject to wear, however, and this is especially true for cords having greater extensibility. So, when an elastic cord is drawn around a corner, the elastic cord is believed to be subject to high wear rates, requiring frequent replacement.

The inventors have discovered that using elastic cords of diminished size, which are doubled, as opposed to one elastic cord that is twice the size of the two cords, can provide a greater ratio of pull back force provided by the doubled cord as compared to the force required to pull the cord out, thereby enhancing the desirability of upper biasing member when it is included the doubled elastic biasing cord as shown in FIG. 4. It will be appreciated that the doubling of the elastic cord in this way also enhances the ability of the assembler to connect the generally non-elastic cord to the elastic cord, as well, because the doubled cord provides a loop at its end, which is easy to tie to. With respect to the generally non-elastic cord 58, it has been discovered by the inventors, and is believed but not relied upon, that a cord or rope of a smaller diameter, which is also strong enough to bear the load that it will be required to bear, will be more desirable as the generally non-elastic portion 58 of the upper biasing member 50 a, because a great portion of the biasing force of the elastic portion 56 of the upper biasing member will actually be translated so as to place that biasing force on the respective arm 22 a or roll bar member 18. It is believed, but is not relied upon, that because the smaller rope or cord will be exposed to less friction as it passes around a corner or over an edge, the biasing force of the elastic cord is not diminished as much as it might be if the cord had a larger diameter. For this reason, the size of the generally non-elastic cord is preferably less than about ½ inch, preferably, less than about ¼ inch in diameter. In the most preferred embodiments, this cord will be about 3/16 of an inch, which is believed to diminish the loss of biasing force as the cord passes around the corner or over the edge. It will be further appreciated that the elastic portion 56 of the upper biasing member 50 a may include a plurality of elastic cords. While simply doubling the elastic cord 56 over to form a double stranded elastic portion will be preferred, it will be further appreciated that it may also be desirable to have a plurality of separated elastic cords or two or more doubled elastic cords. The elastic portion 56 of the upper biasing member 50 a may have any number of elastic cords arranged in any configuration so as to provide a resilient elastic portion that will stretch and then place force against the ends, when the elastic portion is stretched.

Preferably a generally non-elastic cord 58, which is more resistant to abrasion, is interconnected with the elastic cord 56 so that the two-piece biasing member 50 a, 50 b has the attributes of both cords where these attributes are most useful. That is, the elastic portion 56 provides extensibility and elasticity, but is not required to wrap around a corner or over an edge as it passes through a corner guide 66 a, 66 b, 66 c. The generally non-elastic portion 58, which is more resistant to abrasion than the elastic portion, is able to be drawn against the respective hard edges of the corner guides 66 a, 66 b, 66 c when the roll bar member 18 extends away from the latch plate 64 a. The preferred elastic cord will preferable have an extensibility of from about 40% to about 220% greater than its relaxed, unstressed state, preferably from about 60% to about 200%, more preferably from about 90% to about 170%, even more preferably from about 110% to about 150% and most preferably about 130%.

It will be appreciated that the generally non-elastic cord 58 may be any cord that has very limited extensibility and may stretch slightly when the respective ends are drawn apart under at least some force. The extensibility of the elastic cord 56 will generally be at least 10 times, preferably at least 20 times, more preferably at least 30 times as great as the limited extensibility of the generally non-elastic cord 58, which may stretch somewhat, but will not be what is generally recognized to be an elastic cord. The generally non-elastic cord 58 may be made out of a plurality of strands of naturally material such as jute or the like, or a plurality of strands of polymeric rope making material such as polyester, nylon or the like or even wire rope or cable. Metal rope or cable is not generally preferred, however, as it is not generally sufficiently flexible to allow the generally non-elastic cord 58 to wrap around the hard edge of the corner guides 66 a, 66 b, 66 c or truck box 6. In preferred embodiments the generally non-elastic cord 58 will be made of a plurality of strands of polymeric material, woven together to form the generally non-elastic rope or cord, preferably nylon polyester material. In preferred embodiments, the generally non-elastic cord will have a hollow polyester braided jacket and preferably a 3/16 inch polyester core, which may or may not be braided.

Upper biasing members 50 a, 50 b have respective first and second ends 52, 54. As illustrated, each preferred upper biasing member 50 a, 50 b includes an elastic member or cord 56 interconnected to a generally non-elastic portion or cord 58. In this embodiment, a bungee cord 56 is interconnected to a rope 58 made of a durable material, such as nylon (see also, above discussion regarding possible cords). Each upper biasing member 50 a, 50 b is arranged and configured such that in operation, the generally non-elastic portion 58 is the only portion of the upper biasing member 50 a, 50 b that contacts the edge of the truck box 6, or corner guide 66 a, 66 b, 66 c located on the respective corner of the truck box. The generally non-elastic portion 58 is more durable than the elastic cord 56 and thus, can withstand more contact with the respective abrasive corner or corner guide 66 a, 66 b, 66 c. As illustrated, the upper biasing members 50 a, 50 b can be supported along the truck box 6 with one or more respective support guides 68.

The first end 52 of each upper biasing member 50 a, 50 b is preferably retained to the latch plate 64 a with one respective retaining strap 70 that has a plurality of apertures (located behind knotted ends 60, see FIG. 4). The ends 60 of the elastic cord 56 can be threaded through the apertures and secured by, for example, knotting cord ends 60. Additionally, grommets 76 are provided to reinforce the apertures, to strengthen the strap proximate the apertures and to further support and secure the knotted end 60 against the aperture. The retaining strap 70 can be secured to the truck box 6 with a fastener 74. As illustrated in FIGS. 2A-2B and discussed above, a second end 54 of each respective upper biasing member 50 a, 50 b is preferably interconnected to the respective arm 22 a, 22 b (see also, FIG. 1). It will be appreciated that other mechanisms that are known in the art may be used to join the respective cords 56, 58 of the upper biasing members 50 a, 50 b and in securing the biasing members 50 a, 50 b to the truck box 6.

It will be appreciated that a strap 70 material will be selected that can withstand the force placed on the attachment point by the biasing member. It will be further appreciated that the retaining strap 70 is not necessarily made of a flexible material and can be made out of a rigid or semi-rigid material as stated above and that the grommet can be replaced by a washer or the like. The retaining strap 70 is preferably made of woven material; most preferably nylon polyester strap material that is determined to be strong enough to secure the respective upper biasing member 50 a, 50 b to the truck box 6 with out breaking, tearing or otherwise allowing the respective upper biasing member to disconnect from the truck box under normal use conditions. It will be appreciated, that other functionally suitable materials may be used in place of the retaining strap including without limit flexible, semi-rigid or even rigid materials that will include a rigid metal plate.

FIG. 5 schematically illustrates the general movement of the front arm 22 a as viewed from the front end 8 a (not shown in this figure for clarity) of the truck box 6. In preferred embodiments, the shaft 36 a, 36 b of each arm 22 a, 22 b includes a restricting member 38 a such that the sleeve or sliding portion 32 a, 32 b of the arm 22 a, 22 b is prevented from traveling down the shaft 36 a, 36 b, past the respective restricting member 38 a. Restricting the movement of the sleeves 32 a, 32 b downward along the shaft 36 a, 36 b is beneficial in that the elongated roll bar member 18, and thus the tarp 12, will be lifted substantially above apex A of the end caps 8 e, 8 f of the truck box 6 and, as generally shown in FIG. 6A. Grain cargo is often crowned in the center, having a height highest towards the apex A of the end caps 8 e, 8 f. As the elongated roll bar member 18 moves in the unroll direction away from the support posts 65 and toward the latch plate 64 a, the restricting member 38 a associated with the shaft 36 a will prevent the sleeve 32 a, to which the motive source 30 and the elongated roll bar member 18 are attached, from sliding down the shaft 36 a as the arm 22 a reaches the apex A of the end cap 8 e. This will have the effect of raising the motive source 30 and the roll bar 18 up and over and accumulated grain or other cargo C, gathered in the center of the truck box 6 (see, for example, FIG. 6A), as the tarp 12 is unrolled to cover the top opening 7 a (see, for example, FIGS. 7A and 7B). After the tarp 12 is secured and the cargo C settles, spreading out more evenly within the truck box 6, the operator can re-secure the tarp 12 to insure a tighter fit.

When the top opening 7 a is covered by the tarp 12 and the roll bar member 18 is secured against the underside of the latch plate 64 a, the top opening 7 a is covered by the roll-up tarp apparatus 10. When the operator wishes to expose the top opening 7 a when it is covered by the tarp 12, the operator will activate the motor 31 of the motive source 30 so that the elongated roll bar member 18 will initially move down from the underside of the latch plate 64 a, until the tarp 12 is fully unrolled and the roll bar member 18 will then continue to turn in the same direction and begin rolling the tarp 12 up on the roll bar member 18 in the opposite direction, initially climbing upward as it begins to gather the tarp 12. As the roll bar member 18 continues to gather and roll the tarp 12 up on its extended length, the roll bar member 18 will traverse over the latch plate 64 a and then continue to gather or furl the tarp 12 as the roll bar member 18 turns over the upper surfaces 25 of the respective end caps 8 e, 8 f and moving in the roll-up direction. When the roll bar member 18 has gathered or furled all of the tarp 12 it is-positioned adjacent the nexus of the support posts 65 and the area where the tarp 12 is attached to the longitudinal side 8 d of the truck box 6.

As illustrated schematically in FIGS. 7A, 7B and 13B, when the roll-up tarp apparatus 10 is moving in the unroll direction driven by the motive source 30 (or, alternatively, a crank handle as shown in FIG. 23), the elongated roll bar member 18 will eventually traverse over the latch plate 64 a, 64 a′, and then travel down below the latch plate 64 a, 64 a′ until the tarp 12, 12′ is fully unrolled. Preferably, the tarp 12, 12′ is long enough such that the elongated roll bar 18 drops a length L between about 5 to about 15 inches from below the highest point along the radius of the underside of the latch plate 64 d′, more preferably about 7 to about 13 inches, even more preferably about 9 to about 11 inches, even more preferably about 10 inches. The long drop L allows the elongated roll bar member 18 to be secured underneath the latch plate 64 a, 64 a′ even on a windy day, where the elongated roll bar member might bow due to the wind, so that the center of the elongated roll bar member bows, and even when a large load is loaded into the truck box 6 so that it initially extends above the end caps 25 a in the middle before the load settles into the truck box 6. Once the tarp 12 is fully unrolled, the elongated roll bar member 18, still driven by the motor 31 of the motive source 30, will roll-up in an upward direction gathering or rolling-up the tarp 12 until the roll bar member 18 has gathered as much of the tarp 12 that is available within the space that is allowed and it is secured underneath the latch plate 64 a (see also, U.S. Pat. No. 4,505,512 Schmeichel et al., the disclosure of which is hereby incorporated herein by reference).

The restricting members of the present invention may take many forms. In preferred embodiments, the shaft 36 a, 36 b of each arm 22 a, 22 b will include a plurality of adjustment apertures 29 a, 29 b. A preferred restricting member, preferably a bolt 38 a, can be inserted transversely into one of the respective adjustment apertures 29 a, 29 b and interconnected with a reciprocating nut 37 a, which, together, limit the downward distance the sleeve 32 a, 32 b can slide on the respective shaft 36 a, 36 b.

Referring now also to FIG. 6B, an alternative restricting member includes a spring 42 that is placed above the respective restricting member 38 b to generally support the respective sleeve 32 a, and thus the elongated roll bar member 18, above the cargo C in the truck box 6 as the arms 22 a, 22 b direct the elongated roll bar member 18 in the roll-up and unroll directions. It will be understood that the spring 42 of the present invention can be substituted with a variety of resilient materials.

FIGS. 6C-6E show alternative restricting member embodiments that can be used as a substitute for the restricting member 38 a illustrated in FIGS. 6A and 6B. The restricting member of FIG. 6C is a collar 38 c secured on the respective arm 22 a with a fastener 39 c. The restricting member of FIG. 6D is a pin 38 d inserted through one of a plurality of apertures of the respective arm 22 a. The pin 38 d can be secured to the respective arm 22 a with a fastener 39 d. The restricting member of FIG. 6E is a flattened portion 38 e of the respective shaft 36 a formed such that the sleeve 32 a cannot slide below the flattened portion 38 e. It will be understood that the restricting members disclosed are merely illustrative and alternatives will be possible without departing from the spirit and scope of this disclosure.

FIG. 5 additionally illustrates how each upper biasing member 50 a, 50 b assists the movement of the respective arms 22 a, 22 b in the roll-up direction (only the first upper biasing member 50 a is shown but it will be understood that second upper biasing member 50 b is arranged and configured similarly). When the respective arm 22 a is moving in the rolled-up direction (from right to left, as shown in the figure), the upper biasing member 50 a is stretched and tensioned. As the motive source 30 directs the arm 22 a in the unrolled position, the tensioned upper biasing member 50 a urges the arm 22 a to the other side 8 b of the truck box 6, thus assisting the motive source 30. FIG. 5 further illustrates, in phantom, the elongated roll bar member 18 in an open position, wherein the elongated roll bar member 18 has completely rolled-up the flexible cover 12 and the elongated roll bar member 18 and the gather tarp 12 rolled up against the plurality of support posts 65 extending along the longitudinal side 8 d of the truck box 6, opposite the latch plate 64 a (see also, FIG. 1).

Referring now also to FIGS. 9 and 10 that illustrate an alternative and preferred method of securing at least one respective arm 22 a′ to the respective side 8 a, 8 c of the truck box 6 with a bracket or the like 90, 90′. As shown, a bottom end 26 a′ of the arm 22 a′ preferably includes a retaining element or connecting portion 27′ having a socket that corresponds to a ball 93. The ball 93 is provided with a threaded stem that is interconnected to the support member 94. The corresponding connecting portion 27′ and ball 93 collectively form a ball joint 95 to allow for minor adjustments of the longitudinal placement of the top of the respective arm 22 a′ as best illustrated in FIG. 10. The preferred allowed range of movement is at least about 5 degrees, preferably at least about 10 degrees, more preferably at least about 15 degrees and most preferably at least about 20 degrees such that the roll-up tarp apparatus 10 can be effectively used with truck beds having a variety of lengths. For example, if the elongated roll bar member 18 is longer than might be needed, the ball joint 95 will allow for the longer roll bar 18. Moreover, the ball joint 95 is preferred for truck boxes having slanted ends 8 c′ (as shown in phantom in FIG. 10), where it is likely that the arm 22 a′ will have to slant back toward the top of an end cap (see also, FIG. 2A) over the top opening 7 a of the truck box 6. It will be appreciated that such slanted back truck boxes allow haulers to carry more cargo lower to the center of gravity of the trailer and also provide a preferred climbing angle for a hauler wanted to climb up a ladder at the back of the truck box to inspect the cargo load in the truck box.

In alternate preferred embodiments, each respective arm 22 a, 22 b is additionally biased with a lower biasing member 100 as best illustrated in FIGS. 1 and 8, preferably one lower biasing member 100 operatively engaged with each arm 22 a, 22 b. As illustrated most clearly in FIG. 8, preferably one of the respective arms 22 a, 22 b, in this illustration front arm 22 a, is interconnected to the respective side 8 a of the truck box 6 with a mounting bracket 90. The mounting bracket 90 includes opposing feet 91 a with apertures for receiving fastening elements, and a raised section 91 b that is spaced outwardly from the side 8 a of the truck box 6 when the mounting bracket is attached to the truck box. Extending from the raised section 91 b of the mounting bracket 90 is a support member 92 to which one arm 22 a can be rotatably mounted. In this embodiment, the bottom end 26 a of the arm 22 a includes an alternate retaining element 27 configured to be a transverse cylindrical portion that can be connected to the support member 92. The preferred lower biasing member 100 includes a torsion spring 102 positioned on the support member 92 between the mounting bracket 90 and respective arm 22 a. Preferably, a first nut 94 is welded to the support member 92, which is threaded on both ends. The cylindrical retaining portion 27 of the arm 22 a can be slid over the support member 92 and secured thereto by a second nut 96. The lower biasing member 100 having an assisting end or arm 104 with a finger 105 and a static or stationary end 106, with the biasing member 100 arranged and configured such that the lower biasing member will assist the motor 31 of the motive source 30 (see also, FIG. 2A) by applying a force F to the arm 22 a so that the arm 22 a is always urged in the direction of side 8 b of the truck box 6. The mounting bracket 90 preferably includes a stop, a block 98 or similar device to maintain the position of the static or stationary end 106. As illustrated, the finger 105 of the preferred assisting end 104 engages the respective arm 22 a and pushes the respective arm 22 a in the unroll direction. It will be understood that a lower biasing member 100, located proximate the bottom end 26 a of the arm 22 a, can be used in conjunction with or as an alternative to the upper biasing member 50 a located towards the top end 24 a of the respective arm 22 a. A similar lower biasing member is preferably operatively secured to the second arm 22 b.

In an alternate preferred roll-up tarp apparatus 110, as generally illustrated in FIGS. 11-16C operatively connected to a truck box 6, the roll bar biasing member 150 includes a cord 158 having first and second ends 160, 162, one end 162 is interconnected to the elongated roll bar member 18 and the other end 160 is interconnected to a tensioning element 156, such as a spring, which in turn, is interconnected to the truck box 6. Preferably, one roll bar biasing member 150 is attached to each end of the elongated roll bar member 18 although only one is shown for clarity. The preferred tensioning element 156 is a metallic coil spring, versus, for example, an elastic cord, because it is believed that springs generally work better when it is generally at or below freezing and/or there is frost and/or snow on the tarp and/or spring. The inventors have found that the elasticity (or stretchability) of an elastic cord is generally more affected by cold temperatures in comparison to a metallic coil spring. For example, a cold bungee cord will typically lose a significant amount of its elasticity in very cold weather whereas a spring generally will not. The tensioning member 156 is preferably a spring but can be at least one elastic cord or the like having an extensibility of at least about 60% greater that its relaxed, unstressed state, more preferably at least about 100%, even more preferably at least about 130%. One preferred spring is made of music wire or the like having a wire diameter of about 0.148″, an outside coil diameter of about 1.50″, free length of about 14.0″, a spring rate of about 3.6 lbs. per inch, an initial tension of about 10 lbs., a maximum load of about 92 lbs., a maximum deflection of about 23″ and a zinc PL finish or the like.

Biasing member 150 is connected to one longitudinal side 8 b of the truck box 6 such that an unwound portion of the cord 158 and the tensioning element 156 remain generally perpendicular to the elongated roll bar or roll tube 18 during operation. This perpendicular relationship provides for a generally self-adjusting and self-aligning roll bar biasing member in that the unwound portion of the cord 158 will have the tendency to remain generally perpendicular to the elongated roll bar member 18 as the cord 158 is continually tensioned in the direction of the longitudinal side 8 b of the truck box for which the biasing member 150 is secured. Generally, the unwound portion of the respective cord 158 of the respective biasing member 150 remains perpendicular to the elongated roll bar member 18 because of the constant tension exerted on the cord 158. Therefore, the tension exerted on the respective ends of the elongated roll bar member 18 will be generally equal and provide for generally even movement of the ends of the roll bar member. When the cord 158 is being unwound from the elongated roll bar member 18, as the roll bar member moves from the closed position to a fully open position in which the flexible cover or tarp 12 is full wound up upon the elongated roll bar member 18, the force on the cord generally increases and the spring 156 stretches. As the cord unwinds as the elongated roll bar member 18 is on the top of the truck box 6, rolling along support bars 9 and the ridges of the respective end caps 25 a along the edges of the end caps, the cord 158 actually unwinds slower than the tarp 12 gathers or winds up on the roll bar member 18, especially as the tarp thickness on the roll bar 18 begins to grow in thickness, because the cord tends to be gathered directly on the outer surface of the roll bar 18, whereas the thickness of the tarp, as it becomes rolled up upon the roll bar, makes the diameter of the surface upon which the tarp 12 is wound, increasingly greater than the diameter of the roll bar 18 proximate the area where the cord 158 is gathered. For this reason, the cord 158 has to slide over the top 25 of the end cap 8 e proximate the roll bar member 18 and over an edge 64 f′ of the latch plate 64 a in the direction of the roll bar member, even as the spring 156 is being stretched and the force on the cord 158 is being increased, because the cord 158 is being released from the roll bar member 18 at a slower rate than the linear length of the tarp 12 is being gathered or wound up on the roll bar member 18 and at a slower rate than the roll bar member 18 is moving over the top opening 7 a of the truck box 6. When the tarp 12 is being unwound from the roll bar member 18, and the roll bar member is moving from an open position toward a closed position, the tarp 12 is released or unwound faster than the cord 158 is wound up on the roll bar member 18, so, in that case the cord 158 will again slide over the top 25 of the end cap 8 e and over an edge 64 f′ of the latch plate 64 a, but in this case it will be releasing the stress on the spring 156 and sliding back toward the latch plate 64 a.

While the biasing member 150 may be connected directly to the truck box side 8 b, connection via an attachment plate 270 is preferred. One preferred attachment plate 270 includes a base 271 and an extension 272 that is angled with respect to the base 271. The base 271 includes an aperture 273 for receiving a fastener 274 that is used to secure the attachment plate 270 to the truck box side 8 b. The extension 272, which positions the biasing member 150 away from the surface of the truck box side 8 b, includes a slot or channel 275 that is in communication with a tensioning element receiving section 276 having at least one securing ridge 278 with a plurality of serrations. Preferably, the tensioning element 156 is a spring having a portion that can be inserted into the slot or channel 275, moved toward the receiving section 276 and then retained at one of the serrations of the securing ridge 278. It is advantageous to provide a plurality of serrations along the securing ridge 278 so that the position of the tensioning element 156 can be adjusted and less care needs to be taken when locating the proper position in which to secure the attachment plate 270 to the side of the truck box 8 b.

One roll-up tarp apparatus 110 further includes a protective bumper 268 or the like attached to the side 8 b of the truck box 6 proximate the latch plate 64 a, 64 a′ and extending downwardly towards attachment plate 270. The bumper 268 primarily serves to protect the side 8 b from the biasing member 150, which, under tension, can be snapped against the side 8 b of the truck box 6 and cause damage. The bumper 268 can also protect the side 8 b from the roll up tarp apparatus 110 that is improperly secured and which may swing up against the side 8 b. Preferably, the bumper 268 is provided with a somewhat resilient surface so that is able to protect an errant biasing member 150 or elongated roll bar member 18 from damage as well. See, for example, see FIG. 11. In addition, preferred biasing members 150 may be provided with a sheathing or shroud 164 to protect the tensioning element 156 from debris or the like. Preferably, the sheathing is in the form of a flexible sheet of material with two lateral edges and two longitudinal edges. The longitudinal edges can include complimentary fasteners, such as hooks 166 and loops 168, so that the sheathing can easily be secured around and removed from the tensioning element 156 without having remove the tensioning element from the attachment plate 270.

With respect to the roll-up tarp apparatus 110 of FIGS. 11-16C, the general tension exerted by the biasing member on the elongated roll bar member 18 is not constant as the elongated roll bar member rolls or unrolls the flexible cover 12. As is shown in FIG. 18A and the graph depicted in FIG. 22 a (see also Table 1), tension exerted on the elongated roll bar member 18 at the completely secured position (P1) and at the completely open position (P6) is about equal (within about 1 lb.). In addition, it is noted that in this embodiment there is continual tension placed on the elongated roll bar member 18 when the roll bar member is in intermediate, partially-open positions (P4-P4) or partially closed positions (P2-P3) and even when the elongated roll bar member is in the secured or latched position (P1) as is also illustrated in FIG. 16C. Continual tension exerted on the elongated roll bar member 18 when the roll bar member is in the secured or latched position is advantageous because, it has been discovered that it will substantially eliminate lateral swinging of the elongated roll bar member. This, in turn, can prevent damage from the elongated roll bar member by preventing it from repetitively banging against the respective side 8 b of the truck box 6. In addition, if continual tension is exerted on the elongated roll bar member 18, there is a reduced risk that wind gusts could infiltrate under the flexible tarp 12 and lift the tarp up, similar to a sail. This can be a significant problem as wind lifting the tarp 12 up could potentially blow the tarp off of the truck box 6 or otherwise damage the roll up tarp apparatus. Since grain trucks are often used in the plains of the Midwest, where gusty winds are common, the present invention provides a significant advantage as compared to known devices that do not address this problem. It is noted that the amount of tension noted in Table 1, which is illustrated in the graph of FIG. 22 a is simply an example, and that the actual amount of force exerted by a tensioning element can differ based on the particular tensioning element selected as well as the configuration of the roll-up tarp apparatus (see also, FIG. 22 b).

It will be appreciated that alternate roll-up tarp apparatuses may have a tension pattern more similar to what is illustrated in FIG. 22 b. To acquire the data illustrated in FIG. 22 b, a roll-up tarp apparatus was operatively secured to a truck box. The roll-up tarp apparatus was similar to that shown in FIG. 11 and included a biasing member having a spring made of music wire having a wire diameter of 0.148″, an outside coil diameter of 1.50″, a free length of 14.0″, a spring rate of 3.6 lbs. per inch, an initial tension of 10 lbs., a maximum load of 92 lbs., a maximum deflection of 23 in. and a zinc PL finish. The roll-up tarp assembly was operated to open the cover from a secured position P1. At each position (P1-P6) illustrated in FIG. 18A, the movement of the elongated roll bar member 18 was stopped and the length of the spring was measured to indicate the amount of stretch. The various stretch lengths are listed in Table 2 below. Then, to determine the amount of tensioning force exerted by the spring, a pull type scale, preferably a Cabela's Buck Scale (Item No. XJ-226597), was attached to the spring and the spring was stretched to correspond to the length of the spring measured during operation of the roll-up tarp apparatus. Once the length of the spring equaled that measured during operation of the roll-up tarp apparatus, the pounds of tensioning force indicated on the scale were recorded and the record force is listed in Table 2 below. It is noted that the highest amount of tensioning force exerted by the tensioning element (spring) in both FIGS. 22 a and 22 b is highest when the elongated roll bar member is in the secured position and the open position.

TABLE 1 Corresponding Tensioning Force Position (lbs.) P1 54 P2 18 P3 20 P4 25 P5 35 P6 55

TABLE 2 Corresponding Length of Spring Tensioning Force Position (in.) (lbs.) P1 40 235  P2 15.5 66 P3 15.5 66 P4 17 77 P5 20 98 P6 28 155 

As with previous embodiments, when the roll-up tarp apparatus 110 is moving in the unroll direction driven by the motive source 30 (or, alternatively, a crank handle), the elongated roll bar member 18 will eventually traverse over the latch plate 64 a′, and then travel down below the latch plate 64 a′ until the tarp 12 is fully unrolled. Once the tarp 12 is fully unrolled in an unrolled position (P2), the elongated roll bar member 18 can be rolled-up in an upward direction, gathering or rolling-up the tarp 12 until the roll bar 18 has gathered as much of the tarp 12 that is available within the space that is allowed until the roll bar member 18 and the tarp 12 rolled up on the roll bar member 18 engage the latch plate 64 a′ so that the roll bar member 18 is pressed up against the latch plate 64 a′, with the gathered portion of the tarp being “sandwiched” in between, and the roll bar member 18 is fully secured underneath the latch plate 64 a′ in the closed or fully secured position (P1). When the tarp 12 is fully unrolled and then is moving upward to be secured underneath the latch plate 64 a′, as shown in FIG. 16C, the cord 158 and the flexible cover 12 are both being wound around the elongated roll bar member 18 in the same direction with respect to the rotational movement of the elongated roll bar member 18. When the roll bar member 18 is turned to allow the tarp 12 that is wound up on the roll bar member and a portion of the cord 158 that is wound up on the roll bar member to be unwound, as the roll bar member 18 moves from the fully closed or secured position (P1) to the “unwound” position (P2) shown in FIG. 13 and schematically in FIG. 18A, the tension on the roll bar member 18, exerted by the respective biasing elements at each of the respective ends of the roll bar member 18, is the least that it will be at any point in the movement of the roll bar member 18, i.e. from the fully closed position (P1) to the fully open position (P6). In this unwound position (P2), the tension on the each end of the roll bar member 18 is preferably preset so as to maintain sufficient tension to prevent the roll bar member 18 from striking the side of the truck box 6 and/or prevent the roll bar member 18 from being carried upwards over the top of the truck box 6 by a gust of wind that catches the underside of the unwound tarp 12, so that the roll bar member is pulled up and over the truck box. When the elongated roll bar member 18 is in the fully unrolled position (P2), if the roll bar member 18, as shown in FIG. 16B, turns in a clockwise direction as viewed from the front of the truck box 6, the tarp 12 will wind-up on the roll bar member 18 and the cord 158 will also wind-up on the roll bar member 18 as the roll bar member 18 moves toward the closed or fully secured position (P1). When the roll bar member 18 is in the fully unrolled position (P2) and the roll bar member 18 is turned in the opposite direction (counterclockwise direction), the winding direction of the tarp will change. As the tarp 12 begins to be wound in the other direction and the roll bar member 18 moves from the unwound position (P2) to the initial wind-up position (P3), shown schematically in FIG. 18A, the tarp begins to wind-up on the roll bar member 18, but the cord 158 continues to be released from and unwound from the roll bar member 18. As the elongated roll bar member 18 moves over the top 7 of the truck box 6, toward the fully open position (P6), shown schematically in FIG. 18A, the cord 158 is unwinding and the flexible tarp 12 is winding up with respect to the rotational movement of the elongated roll bar member. It will be further appreciated that when the roll bar member 18 moves from the fully open position (P6), shown schematically in FIG. 18A, to the initial wind-up position (P3), shown schematically in FIG. 18A, the cord 158 will wind-up on the roll bar member 18 and the flexible cover 12 will unwind from the elongated roll bar member 18. Because the outer diameter of the wound up tarp on the roll bar member 18 is greater than the diameter of the part of the roll bar member proximate the area where the cord 158 is wound up when the roll bar member 18 is in the open position (P6), it is believed that the cord 158 is wound up on the roll bar member 18 at a linear rate that is less than the linear rate of the release or unwinding of the rolled up portion of the tarp 12 until the roll bar member 18 begins to get close to the side of the trailer 6 where the latch plate 64 a′ is located, which causes the respective cords 158 at each end of the respective roll bar member 18 to slide over the tops 25 of the respective end caps 8 e, 8 f and the respective edges of the latch plate 64 a′. When the roll bar member 18 is moving toward the fully open position (P6) from the initial wind-up position (P3), the cord 158 will slide over the respective tops 25 of the respective end caps 8 e, 8 f, toward the other side of the truck box 6, where the roll bar member 18 will rest when it is in the fully open position (P6), because the tarp 12 will gradually effectively increase the diameter of the rolled-up tarp 12 on the roll bar with respect to the diameter of the portion of the roll bar member 18 where the cord 158 is unwound, as the tarp 12 is so gathered.

It is noted that the cord 158 winds-up around the outer tube 19 b of the elongated roll bar member 18, preferably not around a spool. Unlike roll tarp apparatuses, where the cord winds-up around a spool, the cord 158 generally rolls and is gathered flat on the roll bar member and generally does not gather upon itself as the cord winds around the elongated roll bar member 18. It is also noted that the cord 158 is gathered on and released from a portion of the roll bar member 18 that does not extend beyond the end cap 8 e, 8 f on either end of the trailer 6. It is believed, but not relied upon, that when the cord 158 winds-up around the outer tube 19 b over the end cap 8 e, 8 f, as opposed to being wound around a spool or the like that extends out beyond the end cap on either end of the trailer, it is safer because the cord cannot catch on any ladder or other devices positioned on the ends of the truck box or get in the way of dump gates, doors or the like. Moreover, the cord is further out of the way and protected from passing trees and other objects. Additionally, the cord preferably winds such that the cord does not overlap itself and winds-up in the direction of the tarp (see, for example, FIGS. 12A, 12B), when the roll bar member 18 is going from the unwound position (P2) to the secured position (P1). When spools are used, they are generally used on the end of an elongated roll bar that extends out beyond the end caps so that the cord or cable is out and away from the front or back of the trailer where it can easily be either in the way of other operations or become engaged with passing objects.

Now also referring to FIGS. 18B-18C, it will be understood that biasing members 150′, 150″ and 150″′ may be configured such that they are at least partially located within the truck box 6. Typical truck boxes 6 include a supportive frame 6 a including a skin or shell 6 b secured thereto. Inside the truck box 6 is a hopper 6 c. In various embodiments, a tensioning element 156′, 156″, 156″′ of the respective biasing member 150′, 150″, 150″′ can be secured to a portion of the frame 6 a and the respective cord 158′, 158″, 158″′ can extend out of the truck box 6 via an aperture 6 d in the shell 6 b. Preferably, the aperture 6 d includes a grommet 170 to reduce wear on the cord 158′, 158″, 158″′ and can serve to guide the cord to the elongated roll bar member 18. As shown, the biasing member 150′, 150″, 150″′ can be secured to the frame 6 a at a variety of angles with respect to the side 8 d of the truck box 6.

As best illustrated in FIGS. 12A, 13A and 24-29, the elongated roll bar member 18 preferably includes an inner tube 19 a, an outer tube 19 b having an outwardly opening longitudinal channel 19 c that is in communication with an larger longitudinal channel 19 d, and a spacer elements 19 e that position the inner tube 19 a within the outer tube 19 b. The spacer elements 19 e can be secured to the outer tube 19 b with a screw fastener 19 f or the like. Preferably, the inner tube 19 a serves as an attachment point for the motive source 30 or coupling 323 (further discussed below), and to facilitate the connection between the tube 19 a and the motive source the tube 19 a may project beyond the end of the outer tube 19 b. In preferred embodiments, the flexible cover 12 is provided with an enlarged longitudinal bead that is removably positioned within the longitudinal channel 19 d by feeding the bead into an open end of the channel 19 d and sliding the rest of the cover 12 along the channel 19 c. In further preferred embodiments, as further discussed below, a cord 258 of a biasing member 250 is secured to and unwraps from around the outer tube 19 a as the elongated roll bar member 18 moves into the open position. More specifically, it is important to note that the cord of the biasing member and the flexible tarp are arranged so that they wind about the elongated roll bar member in opposite directions. Thus, for example, as the roll-up tarp assembly 110 is moved from the open position toward the secured or latched position, the tarp is unrolled or unfurled as the cord 158 of the biasing member 150 is being wound about the roll bar. Conversely, as the roll bar 18 is moved from the secured position toward the open position, the cord 158 of the biasing member 150 is unwound from the roll bar as the tarp 12 is being rolled-up or furled about the roll bar. It is also important to distinguish how the tarp 12 and the cord 158 of the biasing member 150 wind about the roll bar 18. As the tarp assembly 110 is moved between the open and secured positions, the cord 158 of the biasing member 150 winds preferably about the roll bar 18 in a spiral or helical manner, while the tarp 12 winds upon itself and its circumference changes. When the tarp 12 rolls upon itself, it also may roll upon portions of the support bars or ribs 9 and/or the upper surface 25 end caps 8 e, 8 f. It will be appreciated that the roll bar 18 circumference increases as the roll bar moves from a position just above the latch plate 64 a, 64 a′ adjacent the second longitudinal side 8 b to the open position adjacent the first longitudinal side 8 d. As the roll bar 18 moves from the second longitudinal side 8 b to the first longitudinal side 8 d, the circumference of the rolled-up tarp 12 becomes significantly larger than the roll bar 18, while the cord 158 unwinds at a constant rate. This creates a distance differential that results in an increase in tension in the cord 158 as the elongated roll bar member 18 and the tarp 12 are moved to the open position. This increased tension is accommodated by the tensioning or spring element 156 of the biasing member 150. When the elongated roll bar member 18 is moved past the latch plate 64 a′ and allowed to continue to unroll until it bottoms out tension is at a minimum. However, as the roll bar 18 continues to rotate in the same direction, the tarp 12 is rolled up against the latch plate 64 a′ and the force exerted by the tensioning member 156 increases. As it turns out, the forces exerted by the biasing member 150 when the roll up tarp assembly 110 is in either the open or secured positions are roughly the same, while the force exerted by the tensioning member 156 when the elongated roll bar member 18 is located between the longitudinal sides 8 b, 8 d of the truck box 6 will be less than the tensioning forces when the elongated roll bar member 18 is in either the open or secured position.

Now also referring to FIGS. 12B and 13B illustrating an alternative flexible tarp 12′ that is secured within the channel 19 c of the elongated roll bar member 18. FIGS. 12B and 13B further illustrate how cord 159 can be secured into channel 19 c by tying a knot 163 in cord 150 and then sliding the knot into the channel. Knot 163 may be preferred over the screw illustrated in FIG. 12A because the knot 163 can be readjusted as desired. Such adjustments are easily made when the roll bar member 18 is in the unwound position (P2), when the tension on the cord 158, created by the biasing element 256, is the least that it will be at any point in the transition from the fully open position (P6) to the fully secured position (P1).

An alternate roll-up tarp apparatus 210 having a roll bar biasing member 250 is generally illustrated in FIGS. 17A-17C. In this illustrated embodiment, the roll bar biasing member 250 is operatively secured to the truck box 6 and includes a cord 258 interconnected to a tensioning element or spring 256 with a clip 264 and a pulley 266. One end 260 of the cord 258 is preferably interconnected to the latch plate 64 a′ and a second end 262 is interconnected to the elongated roll bar member 18, for example, by drilling a hole through the external surface of the outer tube 19 b of the elongated roll bar member 18, extending the cord through the hole and tying a retaining knot in the end 262 of the cord 258 (another option in which the cord is connected to the elongated roll bar member with a screw is illustrated in FIGS. 12-13). In further embodiments (not shown), a knot can be tied in the end of the cord, and the knot can be slipped into the channel 9 c and the pulled tight to secure. This roll bar biasing member 250 is generally less preferred for motorized roll-up tarp apparatuses as it requires about two times the length of cord 258 to stretch the tensioning element or spring 256 as compared to an embodiment utilizing a cord directly connected to the tensioning element as discussed herein. Utilizing a pulley 266 is occasionally preferred, especially when the roll-up tarp apparatus is installed on a trailer 6 having a shorter sidewall. For roll-up tarp apparatuses utilizing a crank arm (see also, FIG. 23), the pulley reduces the amount of force needed to operate the crank arm 400. In essence, when turning the crank arm 400 to position the elongated roll bar member 18 into the secured position, the pulley 266 will require that the spring 256 be stretched half as much than if the cord 258 was directly attached to the spring 256, thereby making it easier to move the elongated roll bar member 18 against the bias of the spring 156. It is further believed that this embodiment may have additional safety features, in that the spring 156 is not stretched significantly in operation, as would be the case if a pulley 266 was not used. The pulley 266 allows for easier rolling up of the tarp 12 without overstretching the spring 256. It is believed, but not relied upon, that the roll-up tarp apparatus 210 applies forces to the elongated roll bar member 18 generally as illustrated in FIG. 22. In alternate embodiments (not shown, multiple pulleys may be used in series to simplify or ease the turning of such a crank arm and/or the cord 158 can be bolted to a side of the truck box 6 or the latch plate 64 a.

Preferably, a second roll bar biasing member (not shown) is additionally provided at the rear end of the elongated roll bar member 18 to assist the motive source 30 in moving the rear end of the elongated roll bar member 18 in the unroll direction uniformly. The second roll bar biasing member is preferably identical to the first roll bar biasing member 250 and is provided so that there is generally uniform tension on the elongated roll bar member 18. The rear biasing member can be connected to the elongated roll bar member 18 in the same manner as the first roll bar biasing member 250 as discussed above.

Preferably, the roll-up tarp assemblies 110, 210 of the present invention are arranged and configured such that a substantial portion of the wound-up cords 158, 258 are stowed underneath the latch plate 64 a′ when the elongated roll bar member 18 is in the latched, secured position (P1). In preferred embodiments, the cord 158, 258 winds around the elongated roll bar member 18 and the wound up portion has a thickness generally no greater than the thickness of the tarp 12 such that the elongated roll bar member 18 can fit snugly under the downwardly facing curved or arcuate surface 64 d, 64 d′ of latch plate 64 a, 64 a′ as illustrated (see, for example, FIGS. 7B, 12 and 16C). When the elongated roll bar member 18 is in the secured position, the tarp 12 is wrapped around the elongated roll bar; the thickness of the tarp will be greater than the thickness of the cord that wrapped around the roll bar member. This separation takes pressure off of the cord that would otherwise exist if the cord was thicker than the tarp material gathered around the roll bar 18 proximate the respective ends of the roll bar 18. In a preferred embodiment (not shown), a webbing material, such as the type of material used to make seat belts for motor vehicles and the like, is sewn into the edge of the tarp 12, thus providing great thickness to the respective edges of the tarp 12 in the area where this thickness is helpful to provide separation from the latch plate 64 a proximate to portion of the cord 158 that is wound up around the roll bar member 18, when the roll bar is in the secured position (P1). This will significantly reduce the likelihood that the cord 158, 258 might be worn or abraded by coming into contact with the bottom surface of the latch plate 64 a.

The cord 158, 258 may be made out of a plurality of woven strands of natural material such as jute or the like, or a plurality of strands of polymeric rope making material such as polyester, nylon or the like or even wire ropes or cables. In preferred embodiments, the generally non-elastic cord will be a nylon polyester braided cord, preferably a 3/16 inch nylon polyester braided cord. With synthetic materials, the cord preferably includes a jacket surrounding an inner cord. Preferably, the inner cord is polyester material and the jacket is made of nylon material. Alternatively, KEVLAR® para-aramid synthetic cord can be used as the inner cord in conjunction with a polyester or nylon jacket, for example. Para-aramid synthetic cord and the like are preferred because they generally do not stretch over time. Metal rope and cables are not generally preferred, however, as they are not generally flexible enough to allow the generally non-elastic cord to slide around the edges of the truck box. In addition, a metal rope and cables are generally more abrasive and can mar surfaces. For embodiments in which a jacket is secured over the inner cord, black is the preferred color for the jacket because it is believed that black will best prevent ultraviolet rays from damaging the inner cord.

The decision to include one or two arms as well as the decision to include what type and location of biasing members is largely customizable. If the roll-up tarp apparatus is to only have one arm, it is preferred that the arm be located on the front end of the truck box to accommodate rear opening style ends as previously discussed. It may be desirable to eliminate any sort of arm or biasing member on the front side of the truck box so that ladders can be more easily positioned proximate the front end of the truck box. Embodiments of the present invention further include an upper biasing member secured to the front arm and a lower biasing member connected to the second, rear arm. In addition, the front arm may include an upper biasing member as well as a lower biasing member, wherein the rear arm could be omitted and the elongated roll bar member could be additionally biased with an upper biasing member secured to the elongated roll bar member with a rotatable collar or the like. Alternatively, only upper or only lower biasing members can be utilized. The number of potential combinations of elements of the present invention is virtually limitless and all can be utilized as desired to create a product embodying characteristics desired for the specific product and purpose. All such combinations are considered within the scope of the invention.

Elongated roll bar members 18 can have a variety of diameters. In preferred embodiments, the elongated roll bar member 18 has a diameter of about three inches. In alternate embodiments, the elongated roll bar member 18 can have a diameter of two inches, more or less. Preferably, the elongated roll bar member 18 has a diameter of about three inches as the inventors have found that this larger elongated roll bar member is less prone to bending or bowing and will remain straighter as the flexible cover is rolled-up and unrolled. In addition, it is believed that a roll bar having a diameter of about three inches will be more able to resist wind and gravitational forces than a smaller diameter elongated roll bar member. Moreover, it is believed that a larger diameter roll bar member 18 will be able to provide for a straighter and more uniform roll-up of the flexible cover 12.

For elongated roll bar members 18 having a larger diameter, for example a diameter of about three inches or more, the motive source 30 is preferably interconnected to a converter unit 300 that allows the motor 31 to provide more torque to the roll bar member 18, as opposed to having to use a more powerful motor (see, for example, FIGS. 19-21). Generally, the converter unit or unit 300 will be a force multiplier such as a chain drive, a gear box, a V-belt drive system or the like that multiplies the force proved by the motor 31. The converter unit 300 is preferably connected to the second or top end 24 a of the arm 22 a, and includes a shaft 322 that is connectable to the elongated roll bar member 18 with a coupler 323. More specifically, one preferred converter unit 300 shown in FIG. 19 includes a u-shaped frame or housing 302 with an input section 304 and an output section 306, with the housing including two side walls 308, 310 connected to each other by a web 312, with the side walls supporting first and second parallel shafts 320, 322 at respective input and output sections 304, 306. In further embodiments, the housing 302 is fully enclosed. The housing 302 is preferably small as a smaller housing will generally have a lower weight. The first and second shafts 320, 322 are rotatably supported by bearing elements 324, and each shaft 320, 322 supports a wheel 326, 328, respectively. The wheels 326, 328, which are preferably located between the side walls of the housing 302, are spaced apart from each other and which are connected to each other by an the endless belt 330, which is also preferably located between the side walls 308, 310 of the housing. Preferably, the wheels 326, 328 are sprockets and the endless belt is a chain 330 that engages teeth 327, 329, respectively, of sprockets 326, 328. The first wheel or sprocket 326, attached to the first shaft 320, is operatively connected to the motor 31, which can also be attached to the housing 302. The second wheel or sprocket 328, attached to the second shaft 322, is connectable to the elongated roll bar member 18. To prevent slippage and/or possible disengagement of the endless belt 330 from the first and second wheels 326, 328 due to slack, the unit 300 may be provided with an adjustable idler wheel 340 secured on shaft 342. Preferably, the circumference of the first wheel or sprocket 326 is smaller than the circumference of the wheel or second sprocket 328 so that the motor 31 will be able to exert a greater amount of torque to the roll bar member 18 than it would in the absence of the device. It will be appreciated that differences between the rotational speeds of the first and second sprockets 326, 328 will generally depend upon the number of teeth 327, 329 of each sprocket. For example, if the number of teeth 327 on the first sprocket 326 is one half the number of teeth 329 on the second sprocket 328, the first sprocket will rotate twice as fast as the second sprocket. However, the second sprocket 328 will have twice the torque of the first sprocket 326. Or, if the number of teeth on the first sprocket is one third of the number of teeth on the second sprocket, the first sprocket will rotate three times as fast as the second sprocket, while the second sprocket will have three times the torque of the first sprocket. In a preferred embodiment, the ratio of the number of teeth of the first sprocket to the number of teeth of the second sprocket is in the range of about 1:1 to about 1:4. More preferably, the ratio is about 1:2. Even more preferably the first sprocket has 12 teeth and the second sprocket has 26 teeth, for a ratio of about 1:2. In preferred embodiments, the motor itself will provide a drive ratio of from 60:1 to 120:1, preferably 90:1, which can then be multiplied by the multiplier effect of the converter unit 300; which, if it is 2:1, would result in a drive ratio of 180:1. Preferably, the multiplier effect of the converter unit 300, shown in FIGS. 19 and 20, is 2.16:1. The preferred, motor and converter unit combination ratio is 194.4:1. As noted in the earlier discussion of the worm gear type motors, which are preferred as a part of the motive source 30 of the present invention, the design of the worm gear acts as a stop to prevent unrolling of the roll bar member 18 when it is in a fully secured or closed position.

Now also referring to FIG. 23, certain preferred embodiments, as additionally discussed above, include a roll-up tarp apparatus having a crank arm assembly 400 for actuating movement of the elongated roll bar member 18. For example, the roll-up tarp apparatus 10 of FIG. 1 can be configured such that instead of including an arm 22 a having a motive source 30, the apparatus includes a crank arm assembly 400 secured to the inner tube 419 a of the elongated roll bar member. The crank arm assembly 400 further includes a shaft 432. Preferably, the inner tube 419 a and the shaft 432 include corresponding adaptors 442, 444 that can be connected to form a universal joint 440. An operator can grasp and rotate the shaft 432 such that the elongated roll bar member will correspondingly rotate to move the roll bar member into the secured or open position, respectively.

Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims. 

1. A roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having a truck box, the truck box having a top opening, two ends and first and second longitudinal sides, the truck box being further equipped with end caps at each of the two ends, wherein each end cap partially covers the top opening; the roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; wherein the tarp can be wound around the elongated roll bar member; an arm connecting the elongated roll bar member to the truck box; wherein the arm can selectively actuate movement of the elongated roll bar member over the top opening of the truck box in both an unroll direction to position the tarp in a secured position and a roll-up direction to secure the tarp in an open position; a latch plate that is arranged and configured to be secured to and extend along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when in the secured position; a biasing member interconnected between the truck box and the elongated roll bar member, the biasing member including: a generally non-elastic cord interconnected to one end of the elongated roll bar member; wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction; and a tensioning element having a first end and a second end, wherein the first end of the tensioning element is interconnected to the cord and the second end of the tensioning element can be interconnected to the second longitudinal side of the truck box when the roll-up tarp apparatus is operatively secured to the truck box, such that the biasing member biases the elongated roll bar member in the unroll direction; wherein the generally non-elastic cord slides over a top surface of one of the end caps and the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 2. The roll-up tarp apparatus of claim 1, wherein the elongated roll bar member includes an outer tube, wherein the cord winds around the outer tube.
 3. The roll-up tarp apparatus of claim 1, wherein the tensioning element is a spring.
 4. The roll-up tarp apparatus of claim 1, wherein the tensioning element is generally perpendicular to the elongated roll bar member.
 5. The roll-up tarp apparatus of claim 1, wherein the biasing member is arranged and configured such that the biasing member places a downwardly directed tension on the elongated roll bar member when the elongated roll bar member is in the secured position underneath the latch plate.
 6. The roll-up tarp apparatus of claim 1, further comprising a motive source that directs movement of the elongated roll bar member, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 7. The roll-up tarp apparatus of claim 6, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supporting a sprocket, the sprockets being spaced apart from each other and connected to each other by an endless chain.
 8. The roll-up tarp apparatus of claim 1, including first and second biasing members, wherein one biasing member is connected to each end of the elongated roll bar member.
 9. The roll-up tarp apparatus of claim 1, wherein the tensioning element is interconnected to the cord with a pulley.
 10. The roll-up tarp apparatus of claim 1, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 11. The roll-up tarp apparatus of claim 1, wherein the arm is a manually operated crank arm.
 12. A combination open top truck trailer and roll-up tarp apparatus, the combination comprising: an open top truck trailer, the open top truck trailer having an open truck box, the truck box having a top, two lateral sides, and first and second longitudinal sides; the truck box being further equipped with an end cap at each end of the two ends, wherein each end cap partially covers the top opening; a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge is interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; an arm connected to the elongated roll bar member; wherein the arm selectively actuates movement of the elongated roll bar member in both an unroll direction to secure the tarp in a secured position and a roll-up direction to secure the tarp in an open position; a latch plate extending along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when in the secured position; a biasing member including: a generally non-elastic cord interconnected to one end of the elongated roll bar member; wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction; a tensioning element having a first end and a second end, wherein the first end of the tensioning element is interconnected to the cord and the second end of the tensioning element interconnected to the second longitudinal side of the truck box; wherein the biasing member biases the elongated roll bar member in the unroll direction; wherein the generally non-elastic cord slides over a top surface of one of the end caps and the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 13. The combination of claim 12, wherein the elongated roll bar member includes an outer tube, wherein the cord winds around the outer tube.
 14. The combination of claim 12, wherein the tensioning element is a spring.
 15. The combination of claim 12, wherein the tensioning element is generally perpendicular to the elongated roll bar member.
 16. The combination of claim 12, wherein the biasing member is arranged and configured such that the biasing member places a downwardly directed tensioning force on the elongated roll bar member when the elongated roll bar member is in the secured position underneath the latch plate.
 17. The combination of claim 12, further comprising a motive source that directs movement of the arm, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 18. The combination of claim 17, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supporting a sprocket, the sprockets being spaced apart from each other and connected to each other by an endless chain.
 19. The combination of claim 12, wherein the tensioning element is interconnected to the cord with a pulley.
 20. The combination of claim 12, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 21. The combination of claim 12, wherein the arm is a manually operated crank arm.
 22. A roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having a truck box, the truck box having a top opening, two ends and first and second longitudinal sides, the roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; wherein, during operation, the tarp can be wound around the elongated roll bar member; an arm being connected to the elongated roll bar member and configured to selectively move the elongated roll bar member over the top opening of the truck box in both an unroll direction to position the tarp over the truck box in a secured position and in a roll-up direction to position the tarp in an open position; a latch plate that is arranged and configured to be secured to and extend along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when in the secured position; a biasing member including: a generally non-elastic cord interconnected to one end of the elongated roll bar member; wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction; and a tensioning element having a first end and a second end, wherein the first end of the tensioning element is interconnected to the cord and the second end of the tensioning element can be interconnected to the second longitudinal side of the truck box such that when the roll-up tarp apparatus is operatively secured to the truck box, the biasing member applies a tensioning force to the elongated roll bar member when the elongated roll bar member is in the secured position; wherein the generally non-elastic cord slides over the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 23. The roll-up tarp apparatus of claim 22, wherein the elongated roll bar member includes an outer tube, wherein the cord winds around the outer tube.
 24. The roll-up tarp apparatus of claim 22, wherein the tensioning element is a spring.
 25. The roll-up tarp apparatus of claim 22, wherein the tensioning element tensioning element is generally perpendicular to the elongated roll bar member.
 26. The roll-up tarp apparatus of claim 22, wherein the biasing member is arranged and configured such that the biasing member places a downwardly directed tensioning force on the elongated roll bar member when the elongated roll bar member is in the secured position underneath the latch plate.
 27. The roll-up tarp apparatus of claim 22, further comprising a motive source that directs movement of the arm, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 28. The roll-up tarp apparatus of claim 27, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supporting a sprocket, the sprockets being spaced apart from each other and connected to each other by an endless chain.
 29. The roll-up tarp apparatus of claim 22, wherein the biasing member is generally perpendicular to the elongated roll bar member.
 30. The roll-up tarp apparatus of claim 22, including first and second biasing members, wherein one biasing member is connected to each end of the elongated roll bar member.
 31. The roll-up tarp apparatus of claim 22, wherein the tensioning element is interconnected to the cord with a pulley.
 32. The roll-up tarp apparatus of claim 22, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 33. The roll-up tarp apparatus of claim 22, wherein the arm is a manually operated crank arm.
 34. A roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having a truck box, the truck box having a top opening, two ends and first and second longitudinal sides, the roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; wherein the tarp can be wound around the elongated roll bar member; an arm being arranged and configured to be interconnected to one of the respective ends of the truck box, the arm securing the elongated roll bar member to the truck box; a motive source being arranged and configured to selectively move the elongated roll bar member over the top opening of the truck box in both an unroll direction to position the tarp in a secured position and a roll-up direction to secure the tarp in an open position; a latch plate that is arranged and configured to be secured to and extend along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when in the secured position; a biasing member including: a generally non-elastic cord having first and second ends, the first end interconnected to one end of the elongated roll bar member and the second end secured to the truck box; wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction; and a tensioning element having a first end and a second end, wherein the first end of the tensioning element is interconnected to the cord with a pulley and the second end of the tensioning element can be interconnected to the second longitudinal side of the truck box such that when the roll-up tarp apparatus is operatively secured to the truck box, the tensioning element is generally perpendicular to the elongated roll bar member and the biasing member biases the elongated roll bar member in the unroll direction.
 35. The roll-up tarp apparatus of claim 34, wherein the elongated roll bar member includes an outer tube, wherein the cord winds around the outer tube.
 36. The roll-up tarp apparatus of claim 34, wherein the tensioning element is a spring.
 37. The roll-up tarp apparatus of claim 34, wherein the tensioning element exerts about the same amount of tensioning force when the elongated roll bar member is in the secured position and when the elongated roll bar member is in the open position.
 38. The roll-up tarp apparatus of claim 34, wherein the biasing member is arranged and configured such that the biasing member places a downwardly directed tensioning force on the elongated roll bar member when the elongated roll bar member is in the secured position underneath the latch plate.
 39. The roll-up tarp apparatus of claim 34, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 40. The roll-up tarp apparatus of claim 39, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supporting a sprocket, the sprockets being spaced apart from each other and connected to each other by an endless chain.
 41. The roll-up tarp apparatus of claim 34, wherein the generally non-elastic cord slides over the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 42. The roll-up tarp apparatus of claim 34, including first and second biasing members, wherein one biasing member is connected to each end of the elongated roll bar member.
 43. The roll-up tarp apparatus of claim 34, wherein the second end of the cord is connected to the truck box with the latch plate.
 44. The roll-up tarp apparatus of claim 34, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 45. The roll-up tarp apparatus of claim 34, wherein the arm is a manually operated crank arm.
 46. A method of maintaining tension on a flexible cover of a roll-up tarp apparatus that is operatively secured to an open top truck trailer, the method comprising the steps of: providing an open top truck trailer, the open top truck trailer having an open truck box, the open truck box having a top, a top opening, two ends, two lateral sides and first and second longitudinal sides; providing a roll-up tarp apparatus including: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge is interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; an arm being connected to the elongated roll bar member and the arm being arranged and configured to selectively move the elongated roll bar member over the top of the truck box in an unroll direction as to position the tarp in a secured position and a roll-up direction to position the tarp in an open position; a latch plate extending along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when the tarp is in the secured position; and a biasing member having a generally non-elastic cord, wherein the biasing member can place a tension on the elongated roll bar member when interconnected thereto; wherein the generally non-elastic cord is positioned such that it slides over the latch plate when the elongated roll bar member moves away from the open position toward the secured position; and interconnecting the biasing member with the elongated roll bar member so as to apply a tensioning force to the elongated roll bar member; wherein the tensioning force is greater when the elongated roll bar member is in the secured position than when the elongated roll bar member is moving over the top opening of the truck box from one longitudinal side to the other.
 47. The method of claim 46, wherein the generally non-elastic cord is interconnected to one end of the elongated roll bar member; wherein the cord can wind around the elongated roll bar member as the arm moves the elongated roll bar member in the unroll direction; the biasing member further including a tensioning element having a first end and a second end, the first end of the tensioning element interconnected to the cord and the second end of the tensioning element interconnected to the second longitudinal side of the truck box such that the tensioning element is generally perpendicular to the elongated roll bar member.
 48. The method of claim 47, wherein the roll-up tarp apparatus includes two biasing members, one biasing member connected to each end of the elongated roll bar member.
 49. The method of claim 46, wherein, while the elongated roll bar member is moving in the roll-up and unroll directions, the unwound portion of the cord remains generally perpendicular to the elongated roll bar member.
 50. The method of claim 46, further comprising a motive source that directs movement of the arm, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 51. The method of claim 50, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supports a sprocket, the sprockets are spaced apart from each other and are connected to each other by an endless chain.
 52. The method of claim 46, wherein the force applied by the biasing member when the elongated roll bar member is in the secured position is greater than when the elongated roll bar member is positioned over the open top truck trailer.
 53. The method of claim 46, wherein the generally non-elastic cord is interconnected to one end of the elongated roll bar member and a tensioning element connected to the cord and the second longitudinal side of the truck box.
 54. The method of claim 53, wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction.
 55. The method of claim 46, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 56. The method of claim 46, wherein the arm is a manually operated crank arm assembly.
 57. A roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having an open truck box, the open truck box having a top opening, two ends and first and second longitudinal sides, the truck box being further equipped with end caps at each of the two ends; the roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; an arm connected to the elongated roll bar member and being arranged and configured to selectively move the elongated roll bar member over the top opening of the truck box in both an unroll direction so as to position the tarp in a secured position and a roll-up direction to position the tarp in an open position when the first longitudinal edge is interconnected to the first longitudinal side; a latch plate that can extend along at least a portion of the second longitudinal side of the truck box when interconnected thereto; wherein the elongated roll bar member is stored underneath the latch plate when the latch plate is interconnected to at least a portion of the second longitudinal side and the tarp is in the secured position; and a biasing member having a generally non-elastic cord that can apply a tensioning force to the elongated roll bar member, when interconnected thereto, wherein the tensioning force applied to the elongated roll bar member is greater when the elongated roll bar member is in the secured position than when the elongated roll bar member is moving over the top opening of the truck box from one lateral side to the other; wherein the generally non-elastic cord slides over a top surface of one of the end caps and the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 58. The roll-up tarp apparatus of claim 57, wherein the cord is interconnected to one end of the elongated roll bar member; wherein the cord can wind around the elongated roll bar member as the roll bar attachment assembly moves the elongated roll bar member in the unroll direction; the biasing member further including a tensioning element having a first end and a second end, the first end of the tensioning element interconnected to the cord and the second end of the tensioning element interconnected to the second longitudinal side of the truck box such that tensioning element is generally perpendicular to the elongated roll bar member.
 59. The roll-up tarp apparatus of claim 58, including two biasing members, one biasing member connected to each end of the elongated roll bar member.
 60. The roll-up tarp apparatus of claim 57, wherein, while the elongated roll bar member is moving in the roll-up and unroll directions, the unwound portion of the cord remains generally perpendicular to the elongated roll bar member when the roll-up tarp assembly is operatively secured to the truck box.
 61. The roll-up tarp apparatus of claim 57, further comprising a motive source to direct movement of the arm, the motive source including a converter unit and a motor, the converter unit having an input section that is connected to the motor and an output section that is connected to the elongated roll bar member.
 62. The roll-up tarp apparatus of claim 61, wherein the converter unit includes first and second parallel shafts at the input and output sections, respectively, each shaft supporting a sprocket, the sprockets being spaced apart from each other and connected to each other by an endless chain.
 63. The roll-up tarp apparatus of claim 57, wherein the force applied by the biasing member when the elongated roll bar member is in the secured position is generally equal to the force applied by the biasing member when the elongated roll bar member is in the open position.
 64. The roll-up tarp apparatus of claim 57, wherein the cord is interconnected to one end of the elongated roll bar member and a tensioning element that can be connected to the second longitudinal side of the truck box.
 65. The roll-up tarp apparatus of claim 64, wherein the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction.
 66. The roll-up tarp apparatus of claim 57, wherein the roll-up tarp apparatus includes two biasing members, one biasing member connected to each end of the elongated roll bar member.
 67. The roll-up tarp apparatus of claim 57, wherein the arm is a motorized arm that is pivotally connected to the truck box.
 68. The roll-up tarp apparatus of claim 57, wherein the arm is a manually operated crank arm assembly.
 69. A roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having a truck box, the truck box having a top opening, two ends and first and second longitudinal sides, the roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; wherein the tarp can be wound around the elongated roll bar member; an arm connected to the elongated roll bar member to the truck box; wherein the arm can selectively actuate movement of the elongated roll bar member over the top opening of the truck box in both an unroll direction to position the tarp in a secured position and a roll-up direction to position the tarp in an open position; a latch plate that is arranged and configured to be secured to and extend along at least a portion of the second longitudinal side of the truck box; wherein the elongated roll bar member is stored underneath the latch plate when in the secured position; a biasing member including: a generally non-elastic cord interconnected to one end of the elongated roll bar member; wherein, when the roll-up tarp apparatus is operatively connected to the truck box, the cord can wind around the elongated roll bar member as the elongated roll bar member moves in the unroll direction; and a tensioning element having a first end and a second end, wherein the first end of the tensioning element is interconnected to the cord and the second end of the tensioning element can be interconnected to the second longitudinal side of the truck box; wherein, when the roll-up tarp apparatus is operatively secured to the truck box, the tarp can be positioned in the secured position by rolling the elongated roll bar member over the latch plate, down in the direction of the tensioning element to an unrolled position and then upwards underneath and proximate to the latch plate; wherein when the elongated roll bar member is moving from the unrolled position to the secured position, both the cord and the tarp rotate in the same direction; wherein the generally non-elastic cord slides over the latch plate when the elongated roll bar member moves away from the open position toward the secured position.
 70. The roll-up tarp apparatus of claim 69, further comprising a motive source being arranged and configured to selectively move the elongated roll bar member over the top opening of the truck box in both the unroll direction to position the tarp in the secured position and the roll-up direction to secure the tarp in the open position.
 71. A motorized roll-up tarp apparatus for attachment to an open top truck trailer, the open top truck trailer having an open truck box, the open truck box having a top opening, two ends and first and second longitudinal sides, the motorized roll-up tarp apparatus comprising: a flexible tarp, the tarp having first and second lateral edges and first and second longitudinal edges; wherein the first longitudinal edge can be interconnected to the first longitudinal side of the truck box; an elongated roll bar member attached to the second longitudinal edge of the tarp; the elongated roll bar member having first and second ends; a converter unit operatively connected to at least one end of the elongated roll bar member; a motive source connected to the converter unit, the motive source providing power to the converter unit so that the converter unit is able to rotate the elongated roll bar member to selectively move the elongated roll bar member over the top opening of the truck box in both an unroll direction so as to position the tarp in a secured position and a roll-up direction to position the tarp in an open position when the first longitudinal edge is interconnected to the first longitudinal side; wherein the drive shaft is connected to input section of the converter unit by a worm gear assembly having interengagable gears; an arm, the arm having an end connected to the converter unit and an end movably connected to the truck box; a latch plate that can extend along at least a portion of the second longitudinal side of the truck box when interconnected thereto; wherein the elongated roll bar member is stored underneath the latch plate when the latch plate is interconnected to at least a portion of the second longitudinal side and the elongated roll bar member is in the secured position; and a biasing member that can apply a tensioning force to the elongated roll bar member.
 72. The motorized roll-up tarp apparatus of claim 71, wherein the converter unit includes an input section to which the motive source is connected and an output section that is connected to the elongated roll bar member, with the input section operatively connected to the output section such that the output section has a slower rotational speed than the rotational speed of the input section.
 73. The motorized roll-up tarp apparatus of claim 72, wherein the motive source comprises a motor with a drive shaft, with the drive shaft connected to the input section of the converter unit such that the rotational speed of the input section is slower than the rotational speed of the elongated roll bar member.
 74. The motorized roll-up tarp apparatus of claim 72, wherein the input section and the output section of the converter unit comprise first and second rotatable shafts, with the first and second rotatable shafts drivably connected to each other by an endless belt.
 75. The motorized roll-up tarp of claim 74, further comprising first and second wheels connected to the first and second rotatable shafts, wherein the first and second wheels are drivingly engaged by the endless belt. 